KR20190040379A - A single packet reflective polarizer having an adjusted thickness profile for low color at an oblique angle - Google Patents

Abstract

Multilayer optical film reflective polarizers previously considered to have excessive off-axis color can be used in an " on-glass " configuration in which they are laminated to a back-absorption polarizer of a display, without any light- LC display can provide adequate performance. The reflective polarizer is a TOP (tentered-one-packet) multilayer film that has only one packet of microlayers and is oriented using a standard tenter so that the birefringent microlayers of the film are birefringent birefringent. The thickness profile of optical repeat units (ORUs) in the microlayer packet is adjusted to avoid excessive background color at the vertical and tilt angles. The color at high oblique angles in the white state of the display is determined by locating the thicker ORUs closer to the absorbance polariser and by the average slope from ORU 600 to ORU 645 Is less than 1.8 times the average slope from the ORU 450 to the ORU 600.

Description

A single packet reflective polarizer having an adjusted thickness profile for low color at an oblique angle

The present invention relates generally to multilayer optical film reflective polarizing films, particularly those films having only one packet or stack of alternating polymeric microlayers, some of which are biaxially birefringent, and such reflective polarizers used in displays Lt; RTI ID = 0.0 > lamellas < / RTI > The present invention also relates to related articles, systems and methods.

Reflective polarizers are typically used to enhance the brightness of liquid crystal (LC) displays and display systems. An LC display system typically includes an LC panel, followed by a lighting assembly or backlight positioned to provide light to the LC panel. Brightness enhancement is provided by the reflective polarizer as a result of the optical recycling process: light that can not contribute to the display output (because of its polarization state) is reflected back into the backlight by the reflective polarizer, where it can contribute to the display output, And a portion of the light that is directed to the user or observer is re-reflected toward the reflective polarizer in a different polarization state.

The LC panel comprises a layer of liquid crystal material disposed between the glass panel plates. In addition, the LC panel is sandwiched between two absorbent polarizer films, a front absorbent polarizer attached to the front glass plate of the LC panel, and a back absorbent polarizer attached to the rear glass plate. The brightness enhancing reflective polarizer is placed somewhere behind the LC panel and behind the back absorption polarizer.

Indeed, the design details of the reflective polarizer affect what exactly the reflective polarizer can be placed in the display system to provide optimal, or at least acceptable, optical performance. Some types of reflective polarizers can be directly laminated to the exposed back surface of the back absorption polarizer. One of ordinary skill in the art would believe that these types of reflective polarizers need to have a very low perceived color for the state of polarization (both where light propagates along the optical axis of the display system) and at the highly oblique incidence . This is referred to as the " on-glass " configuration of the reflective polarizer since the reflective polarizer is attached to the back-absorbing polarizer, and then the back-absorbing polarizer is typically attached to the rear glass plate of the LC panel. One reflective polarizer currently used in an on-glass construction is a parabolically-stretched reflective polarizer, discussed further below. Another reflective polarizer used in on-glass construction is a multipacket reflective polarizer, which is also discussed below.

Other types of reflective polarizers that are now considered by those of ordinary skill in the art to have excessive saturation with respect to the state of polarization of polarized light for tilted incident light are not laminated to the back absorption polarizer of the display because the (undesirable) color associated with the reflective polarizer Will be visible to the user through the absorption polarizer and through the LC display. Instead, as these multilayer optical film reflective polarizers of alternating polymer layers with only one packet of reflective polarizers of these latter types-micron layers, the microlayer packet has a thickness gradient or profile to provide broadband reflection, The multilayer optical film is oriented using a standard tenter such that the birefringent layers of the film are birefringent birefringent and such films are referred to herein as " TOP " (Tentered-One-Packet) Is used in a display system as a stand-alone film that is separated from the back-absorption polarizer by at least one air gap, and is attached to a light-diffusing film or layer disposed between the reflective polarizer and the back-absorption polarizer. The light diffusing layer has a significant turbidity value to effectively combine the rays passing through the reflective polarizer in different directions to reduce or eliminate the color associated with the TOP reflective polarizer in terms of the user or observer.

U.S. Patent No. 7,791,687 (Weber et al.) Discloses that a display panel has a combination of a first absorption polarizer and a TOP reflective polarizer on one side thereof-these two polarizers are aligned with each other-on the other side of the display panel It appears to reverse these dominant views by disclosing embodiments having a second absorbing polarizer that intersects the first absorbing polarizer (oriented 90 degrees relative thereto). However, the '687 Weber patent refers to special cases where the first absorbing polarizer is a low contrast absorbing polarizer (e.g., see column 2, lines 1 to 15, and column 3, lines 22 to 39). In the examples, the first absorbing polarizer has a contrast ratio of only about 5 (e.g., see Example 2 where the blocking state transmittance of the first absorbing polarizer is reported as 20%). The '687 Weber patent says that in these cases where the first absorption polarizer has low contrast, the optical properties of the reflective polarizer become more important for maintaining the contrast of the display (see column 3, line 22 to line 39). As evidenced by the examples, the '687 Weber patent then evaluates the display contrast by evaluating the blocking (dark) performance of the display. That is, this patent describes a method for calculating and / or controlling spectral transmittance through crossed polarizer systems in which a TOP reflective polarizer / first absorbing polarizer combination (of low contrast and aligned with the TOP polarizer) is crossed with a high contrast second absorbing polarizer Compare. These transmission spectra are calculated for various oblique declination angles? And an azimuth angle? Of 45 degrees. The calculated transmittance through such crossed polarizer systems represents the dark state of the display and is therefore very low - all examples have transmissivities of less than 4% over the entire visible wavelength range for the angles tested, some have a transmittance of less than 1% Much less. Examples are the systems in which the TOP reflective polarizer is oriented in different ways - some comparing the calculated transmission spectra of their TOP spectral polarizers, in which the thickness profiles are oriented in one way and some are oriented in an opposite manner do. This analysis led the 687 Weber researchers to conclude that the thickness profile of the TOP reflective polarizer should be oriented such that the majority of layers with smaller optical thickness are positioned closer to the display panel than those with larger optical thickness. In embodiments in which the TOP reflective polarizer / low contrast absorptive polarizer combination is disposed behind (rather than forward of) the display panel, this means that the thickness profile of the TOP polarizer is such that the thinner layers face forward, i.e. towards the user, Meaning that the thick layers should be oriented rearward, i. E. Away from the user and towards the backlight.

Modern display systems using a high contrast absorption polarizer both at the front and at the rear of the LC display panel due to the significant color produced by conventional TOP polarizers in the pass state (white state) of the display system at highly oblique incidence angles In view of the current dominant view that top reflective polarizers are not suitable for on-glass applications in the field, we again discussed the suitability of TOP reflective polarizers for these applications. Briefly, the present inventors have found that it is practically feasible to use TOP reflective polarizers in an on-glass configuration in such display systems, i.e., laminated to a high contrast absorber polarizer at the back of the display panel . The present inventors have also found that undesirable visible color at high tilt angles in the white state of the display can be achieved at an acceptable level by properly orienting the TOP polariser and appropriately adjusting the layer thickness profile associated with the thick microlayer end of the microlayer packet Can be substantially reduced. Interestingly, the orientation-thicker microlayers (more precisely, thicker optical repeat units (ORUs)) of the TOP polarisers we found to be optimal are located in front of the display Oriented (more precisely, thinner ORUs) to the rear of the display is the opposite of the orientation taught by the '687 Weber et al. Patent.

Properly designed and oriented TOP reflective polarizers can provide acceptable performance in an LC display, in an on-glass configuration, without the need for any air gap or high turbidity light-diffusing layer. Thus, a laminate made by combining such a TOP reflective polarizer with a high contrast absorbing polarizer can be used without air gaps and without a high turbidity light diffusion layer or structure between the reflective polarizer and the absorption polarizer (and in some cases any significant light diffusion layer or structure Can be used successfully and integrated into a liquid crystal display or the like. TOP reflective polarizers of this structure are multilayer optical films of alternating polymeric layers having only one packet of microlayers, and the multilayer optical film is a multilayer film wherein the birefringent layers of the film (including the microlayers) . ≪ / RTI > Fine layers in the packet, or more precisely ORUs in the packet, are provided with an appropriately adjusted thickness profile to avoid vertical angles to the passing state (white state) of the display system and excessive background color at highly inclined angles. Such TOP multilayer optical film reflective polarizers are further discussed below.

Accordingly, the present inventors herein specifically describe reflective polarizers having only one packet of microlayers that reflect and transmit light by optical interference, the packets of microlayers having a first pass axis y ), A first block axis (x), and a first thickness axis (z) perpendicular to the first pass axis and the first minor axis. The packet of microlayers may comprise alternating first and second microlayers, at least the first microlayers being biaxial birefringent. Pairs of adjacent first and second microlayers form optical repeat units (ORUs) along a packet of microlayers, wherein the ORUs are arranged in a physical (not shown) fashion with a gradient providing a broad band reflectance for the vertically- Define the thickness profile. The ORUs have respective resonant wavelengths as a function of physical thickness profile and optical geometry shape. The ORUs include a first ORU and a last ORU at opposite ends of the packet. ORUs that are close to the last ORU have an average physical thickness that is greater than the average physical thickness of the ORUs proximate to the first ORU. The intrinsic bandwidth-based boxcar average of the physical thickness profile yields an IB-planarized thickness profile, wherein the IB-planarized thickness profile is defined in each of the ORUs. ORUs include an ORU (450), an ORU (600), and an ORU (645). The ORU 450 has a resonant wavelength for an IB-planarized thickness profile of 450 nm or greater for a tilted optical geometry that P-polarized light is incident on the x-z plane at a 80 degree angle of declination ([theta]). All ORUs placed on the sides of the ORU 450 including the first ORU have resonant wavelengths for the IB-planarized thickness profile of less than 450 nm for the tilted optical geometry. ORU 600 and ORU 645 are similarly defined and have resonant wavelengths of 600 nm and 645 nm, respectively, in the same tilted optical geometry. The physical thickness profile of the packet is such that the IB-planarized thickness profile has a first average slope ranging from ORU 450 to ORU 600 and a second average slope ranging from ORU 600 to ORU 645 And the ratio of the second mean slope to the first mean slope is adjusted to be 1.8 or less.

By satisfying this condition, the TOP reflective polarizer, and the laminate to which it is part, is capable of: - in white light passing through it at highly inclined angles - in the case of a display comprising such a polarizer or laminate, Can be given a predetermined amount of color that is close enough to allow neutral white or target white to be acceptable.

The present inventors also describe laminates in which such a reflective polarizer is combined with an absorbance polarizer. The absorption polarizer has a second passage axis and a second blocking axis, and has a high contrast ratio, for example, a contrast ratio of 1000 or more. The absorption polarizers are attached to the reflective polarizer such that there is no air gap between them and the first and second pass axes are substantially aligned. The reflective polarizer is oriented with respect to the absorption polarizer such that the last ORU is closer to the absorption polarizer than the first ORU.

Related methods, systems, and articles are also discussed.

These and other aspects of the present application will become apparent from the following detailed description. In any case, however, the above summary is not to be construed as a limitation on the claimed subject matter, which is limited only by the appended claims, which may be amended during the course of the proceedings.

1 is a schematic side view or cross-sectional view of a liquid crystal display system.
Figure 2 is a schematic side view or cross-sectional view of a single packet multilayer optical film configured as a reflective polarizer.
3 is a perspective view of a web of an optical film.
Figure 4 is a perspective view of an optical film or laminate in relation to a Cartesian coordinate system.
Figure 5 is a schematic perspective view of a multilayer optical film reflective polarizer disposed behind and spaced from the absorption polarizer, wherein a reflective polarizer is provided with a light diffusing layer to reduce the amount of color observed.
6 is a schematic perspective view of a laminate of a multilayer optical film reflective polarizer and an absorptive polarizer without a light diffusing layer.
Figure 7 is a schematic perspective view of a laminate similar to the laminate of Figure 6, but further comprising a glass layer from a liquid crystal panel, wherein an absorption polarizer is disposed between the reflective polarizer and the glass layer.
Figure 8a is a simplified graph for an exemplary purpose of a first physical thickness profile and a boxcar-smoothed thickness profile for a microlayer packet-packet of a TOP reflective polarizer including exactly 15 ORUs , Figure 8b is for the same embodiment but is a corresponding simplified graph showing the resonance wavelength for a boxcar planarized thickness profile and for a given optical geometry shape.
Figure 9 is a graph of eight different but related physical thickness profiles that can be used in a TOP reflective polarizer, the performance of which is modeled and shown in Figures 10a-c.
10A is a composite graph plotting the ORU thickness versus the number of ORUs and plotting the resonant wavelength with respect to the number of ORUs, FIG. 10B is a graph of the slope of the averaged thickness profile of FIG. 10A as a function of the resonant wavelength, 10c is a graph of the calculated color of light transmitted through a laminate of a TOP reflective polarizer and a high contrast absorber polarizer over a range of azimuthal angles phi and azimuths [theta] and the TOP reflective polarizer has a thickness profile of Fig. 10a.
Figs. 11A, 12A, 13A, 14A, 15A, 16A and 17A are composite graphs similar to the composite graph of Fig. 10A but for different TOP reflective polarizer embodiments, and Figs. 11B, 12B, Figures 13b, 14b, 15b, 16b and 17b are graphs similar to the graph of Figure 10b but for such other TOP polariser embodiments, and Figures 11c, 12c, 13c, 14c, 15c, 16c , And 17C are graphs similar to the graph of FIG. 10C but for such other TOP polariser embodiments.
FIG. 18 is a graph of eight different but related physical thickness profiles that can be used in a TOP reflective polarizer, the performance of which is modeled and shown in FIGS. 19A-C.
19A is a composite graph plotting the ORU thickness with respect to the number of ORUs and plotting the resonant wavelength with respect to the number of ORUs, Fig. 19B is a graph of the slope of the averaged thickness profile of Fig. 19A as a function of the resonant wavelength, 19c is a graph of the calculated color of light transmitted through a laminate of a TOP reflective polarizer and a high contrast absorbing polarizer over a range of azimuthal angles phi and azimuths [theta] and the TOP polarizer has the thickness profile of Fig. 19a.
20A, 21A, 22A, 23A, 24A, 25A and 26A are composite graphs similar to the composite graph of FIG. 19A but for different TOP reflective polarizer embodiments, and FIGS. 20B, Figures 22b, 23b, 24b, 25b and 26b are graphs similar to the graph of Figure 19b but for such other TOP polariser embodiments and Figures 20c, 21c, 22c, 23c, 24c, 25c and 26c are graphs similar to the graph of Figure 19c but for such other TOP polariser embodiments.
Figure 27 is a graph of three different but related physical thickness profiles that can be used in a TOP reflective polarizer, the performance of which is modeled and shown in Figures 28A-C.
28A is a composite graph plotting the ORU thickness with respect to the number of ORUs and plotting the resonant wavelength with respect to the number of ORUs, Fig. 28B is a graph of the slope of the averaged thickness profile of Fig. 28A as a function of the resonant wavelength, 28c is a graph of the calculated color of light transmitted through a laminate of a TOP reflective polarizer and a high contrast absorptive polarizer over a range of azimuthal angles phi and azimuths [theta] and the TOP polarizer has a thickness profile of Fig. 28a.
29A and 30A are composite graphs similar to the composite graph of FIG. 28A but for different TOP multilayer optical film reflector polarizer embodiments, FIGS. 29B and 30B are similar to the graph of FIG. 28B, but such other TOP polarizer embodiments And Figs. 20c, 21c, 22c, 23c, 24c, 25c and 26c are graphs similar to the graph of Fig. 19c but for such other TOP polariser embodiments.
Figure 31 is a graph of the measured physical thickness profile for an exemplary TOP multilayer optical film reflective polarizer produced and tested.
32A is a composite graph plotting the ORU thickness with respect to the number of ORUs and plotting the resonant wavelength with respect to the number of ORUs, Fig. 32B is a graph of the slope of the averaged thickness profile of Fig. 32A as a function of the resonant wavelength, 32c is a graph of the calculated color of light transmitted through a laminate of a TOP reflective polarizer and a high contrast absorbing polarizer over a range of azimuthal angles phi and azimuths [theta] and the TOP polarizer has a thickness profile of Figure 32a.
33 is a graph of the measured physical thickness profile for the (known) TOP reflective polarizer of a comparative example.
34A is a composite graph plotting the ORU thickness with respect to the number of ORUs and plotting the resonant wavelength with respect to the number of ORUs, Fig. 34B is a graph of the slope of the averaged thickness profile of Fig. 34A as a function of the resonant wavelength, 34c is a graph of the calculated color of light transmitted through a laminate of a TOP reflective polarizer and a high contrast absorber polarizer over a range of azimuthal angles phi and azimuths [theta] and the TOP polarizer has a thickness profile of Figure 34a.
35 is a graph of the measured physical thickness profile for a TOP multilayer optical film reflective polarizer (known) of another comparative example.
36A is a composite graph plotting the ORU thickness with respect to the number of ORUs and plotting the resonance wavelength with respect to the number of ORUs, FIG. 36B is a graph of the slope of the averaged thickness profile of FIG. 36A as a function of the resonant wavelength, 36c is a graph of the calculated color of light transmitted through a laminate of the TOP multilayer optical film reflective polarizer and the high contrast absorbing polarizer over a range of azimuthal angles ϕ and azimuths [ .
In the drawings, like reference numerals refer to like elements.

As discussed above, the inventors have found that TOP multi-layer optical film reflective polarizers, which are generally considered to have too much off-axis color to be used in an on-glass configuration with a high contrast absorption polarizer, Configuration can actually provide adequate performance. No air gap or high turbidity light diffusing layer is required (and in some cases no light diffusing layer or structure at all) between the TOP reflective polarizer and the absorptive polarizer, or anywhere in the laminate comprising these two polarizers, Nothing is provided. The high contrast absorption polarizer is generally located behind the LC panel in the LC display, which may also include a high contrast absorption polarizer in front of the LC panel, as well as front and rear glass plates as described above.

The TOP reflective polarizer has only one packet of the microlayers and the birefringent microlayers in the film are oriented using a standard tenter to be biaxially birefringent as a result of constrained stretching of the tenter. Moreover, the microlayers in a single packet - or rather optical repeat units (ORUs) defined by the microlayers - have a suitably adjusted thickness profile. The thickness profile is adjusted such that the thicker ORUs in the microlayer packet are closer to the absorbance polariser than the thinner ORUs. The thickness profile may be further adjusted (as described further below) to provide a surprisingly small amount of subtle color in the light transmitted at highly inclined angles through the TOP reflective polarizer (and through the laminate it is part of) do. By so adjusting the thickness profile of the microlayer packet, the TOP reflective polarizer, when combined with a high contrast absorption polarizer, can provide an acceptable on-glass laminate for use in an LC display. Appropriate color performance can be achieved at both normal incidence and oblique incidence, up to a confining angle [theta] of 80 degrees or more and at intermediate azimuth angles [phi] of 0 to 90 degrees.

In general, given a multilayer optical film reflective polarizer of unspecified design, a suitable arrangement in the LC display system of such reflective polarizers is, among other things, the color characteristics of the reflective polarizer, especially the high off- Is a function of color properties. Good color performance is more difficult to achieve at highly inclined angles than at normal incidence. The color properties are then a function of the manner in which the film is made and the resulting physical and optical characteristics of the film.

For example, tens or hundreds or thousands of alternating layers of polymer may be co-extruded through a die, and optionally, by dividing and re-stacking the flow stream in a layer multiplier device, To cool the extrudate on a casting wheel and to reduce the film thickness so that the individual polymer layers form optically thin microlayers and to reduce birefringence on at least a portion of the microlayers, It is known to produce a reflective polarizer by orienting (stretching) the film. In a completed multilayer optical film, the microlayers are characterized by a refractive index difference between adjacent microlayers, an optical thickness of a pair of adjacent microlayers, and a thickness profile of the laminate of such layer pairs along the thickness direction or axis of the film, To reflect and transmit light. In order to produce a reflective polarizer, orientation or stretching is generally performed along one in-plane direction so that the refractive index of the microlayers is differentiated by the difference of the high reflectivity axis, the low reflectance (and high transmittance) Thereby defining a thickness axis perpendicular to the axis and the minor axis. See, for example, U.S. Patent No. 5,882,774 (Jonza et al.).

FIG. 1 is provided for reference to illustrate various components, layers, and films that may be included in a typical LC display system 100. The display system 100 includes a display panel 150 and an illumination assembly 101 positioned behind the panel 150 to provide light thereto. Display panel 150 may include any suitable type of display. In the illustrated embodiment, display panel 150 includes an LC panel (hereinafter referred to as LC panel 150) or an LC panel. LC panel 150 typically includes a liquid crystal (LC) layer 152 disposed between panel plates 154a, 154b (collectively 154). Plates 154 are often made of glass and may include electrode structures and alignment layers for controlling the orientation of the liquid crystals in the LC layer 152 on their inner surfaces. These electrode structures are typically arranged to define regions of the LC panel pixels, i.e. the LC layer, in which the orientation of the liquid crystals can be controlled independently of adjacent regions. The color filter also includes one or more plates 152 for imposing desired colors, such as red, green, and blue, on the subpixel elements of the LC layer and thus the image displayed by the LC panel 150 can do.

The LC panel 150 is positioned between the front (or top) absorption polarizer 156 and the rear (or bottom) absorption polarizer 158. In the illustrated embodiment, the front and rear absorbing polarizers 156 and 158 are located outside the LC panel 150. [ Often, the absorption polarizer 156 or 158 is laminated to the outer major surface of its neighboring glass panel plate (154a or 154b, respectively) with a suitable transparent adhesive. The absorption polarizers 156 and 158 and the LC panel 150 are combined to control the transmittance of light through the display system 100 from the backlight 110 to the observer. For example, the absorption polarizers 156 and 158 may be arranged such that their passing axes (transmission axes) are perpendicular to each other. For example, due to the selective activation of different pixels of the LC layer 152 by the controller 104, light travels through the display system 100 at a desired desired location and thus forms an image to be viewed by the observer. The controller 104 may include, for example, a computer or television controller that receives and displays television images.

For example, one or more optional layers 157 may be provided in proximity to the front absorbent polarizer 156 to provide mechanical and / or environmental protection to the display surface. For example, the layer 157 may include a hardcoat on the front absorbing polarizer 156.

The illumination assembly 101 includes one or more light management films within the array 140 positioned between the backlight 110 and the backlight 110 and the LC panel 150. The backlight 110 may or may not include any known suitable design backlight. For example, the light source (s) within the backlight may be positioned such that the backlight may be of the edge-lit type or the direct-lit type. The light source (s) may include fluorescent bulbs or lamps including cold cathode fluorescent lamps (CCFLs); Or by a combination of arrays of individual LEDs or LEDs, typically different colored LED die chips (e.g., RGB), or by a blue or UV LED die that illuminates and excites the white or yellow emitting phosphor, And any of the known light sources including one or more of the LEDs emitting the nominal white light.

An array of light management films 140, also referred to as a light management unit, is positioned between the backlight 110 and the LC panel 150. The light management films affect the illumination light propagating from the backlight 110. In some cases, the backlight 110 may be considered to include one, some, or all of the light management films in the array 140.

The array of light management films 140 may include a diffuser 148. The diffuser 148 is used to scatter or diffuse the light received from the backlight 110. The diffuser 148 may be any suitable diffuser film or plate. For example, diffuser 148 may comprise any suitable diffusing material or materials. In some embodiments, the diffuser 148 may comprise a polymer matrix of polymethylmethacrylate (PMMA) having various dispersed phases including glass, polystyrene beads and CaCO ₃ particles. The diffuser 148 may also be or include a 3M ™ Scotchcal ™ diffuser film type 3635-30, 3635-70, and 3635-100, available from 3M Company, St. Paul, Minn. can do. The diffuser 148 as used in the light management film array, such as the array 140, typically comprises a light source such as BYK < RTI ID = 0.0 > (BYK) < / RTI > of Silver Springs, Maryland, USA according to a suitable procedure as described in ASTM D1003. Will have a relative turbidity of, for example, greater than 40% when measured using a Haze Guard Plus turbidity meter from Sun-Gardiner.

The light management unit 140 also includes a reflective polarizer 142. Although in general terms the reflective polarizer 142 may be of any suitable design - for example, a multilayer optical film, a diffuse reflective polarizing film (DRPF) such as a continuous / dispersive phase polarizer, a wire grid reflective polarizer, or a cholesteric reflective Polarizers, but for purposes of the present application, the present inventors are interested in those cases where the reflective polarizer is a specific type of multilayer optical film, as discussed elsewhere herein. For example, the reflective polarizer may be a TOP reflective polarizer as described above. One of ordinary skill in the art will appreciate that this type of reflective polarizer may be used in combination with the reflective polarizer 142 and the rear absorbent (not shown) to maintain the entire imaging color of the display system 100 at or reasonably close to the intermediate white, A high turbidity diffuser between the polarizers 158 and air gaps was considered to have many off-axis colors to be considered necessary.

In some embodiments, a polarization control layer 144, such as a quarter wave retarding layer, may be provided between the diffuser 148 and the reflective polarizer 142. The polarization control layer 144 may be used to change the polarization of the light reflected from the reflective polarizer 142 so that an increased fraction of the recycled light is transmitted through the reflective polarizer 142.

The array of light management films 140 may also include one or more brightness enhancement layers. The brightness enhancement layer can redirect the off-axis light to a direction closer to the axis of the display. This increases the amount of light propagating on-axis through the LC layer 152, thereby increasing the brightness of the image viewed by the observer. One example of a brightness enhancement layer is a prismatic brightness enhancement layer, which has a plurality of prismatic ridges that redirect illumination light through refraction and reflection. In Figure 1, the first prismatic brightness enhancement layer 146a provides optical gain in one dimension and the second prismatic brightness enhancement layer 146b is oriented in a direction orthogonal to the prismatic structures of layer 146a By having prismatic structures, the combination of layers 146a and 146b increases the optical gain of display system 100 to two orthogonal dimensions. In some embodiments, the brightness enhancement layers 146a and 146b may be positioned between the backlight 110 and the reflective polarizer 142. [

The different layers of the light management unit 140 may be independent of each other. Alternatively, two or more layers of the light management unit 140 may be laminated to each other.

Two design aspects of a multilayer optical film reflective polarizer for use in an LC display system are of particular relevance to the present application: the manner in which the extruded film is stretched, which, for a practical effect, results in birefringent microlayers uniaxially birefringent or doubly birefringent, and whether the layer multiplexer devices are used during manufacture, or whether the completed multilayer optical film has more than one distinct stack or packet of microlayers.

First, a method of stretching or orienting the extruded film is discussed. In a first known technique, the length of the polymer film or the web is continuously advanced through a standard tenter device. In a standard tenter, the film is held tight by sets of clips attached to opposing edges of the film and the clip sets move forward along the rails under the action of a chain drive or the like. In one section of the tenter, the straight sections of the rails are spaced apart so that when the clips transport the film generally forward in the down-web direction (also referred to as the longitudinal direction), the clips move the film to the cross- cross-web direction (also referred to as a transverse direction). This orientates the film primarily in the cross-web direction. The clips of the standard tenter maintain a constant clip-to-clip spacing and travel at a constant speed over the entire length of the straight rail sections, which prevents the film from relaxing in the down-web direction. Due to this down-web confinement of the film during orientation, the stretching provided by such a standard tenter is sometimes referred to as constrained stretching. As a result of the constraint, the layers in the film that become birefringent under the conditions of stretching are typically oriented in three main directions of the film: cross-web or x-direction, down-web or y- To produce three different refractive indices. Let nx, ny, and nz denote the refractive indices of such layers along the main x-direction, y-direction, and z-direction, nx ≠ ny, ny ≠ nz, and nz ≠ nx. (The refractive index is specified to a specific visible wavelength, such as 550 nm (green) or 632.8 nm (He-Ne laser, red), so long as the dispersion appears in the material and thus the given index of refraction n is somewhat modified as a function of the optical wavelength Or the refractive index can be understood to be an average for a visible wavelength range, for example, from 400 nm to 700 nm.) Materials with this type of birefringence are referred to as being birefringent birefringent

In a reflective polarizer where birefringent microlayers alternate with isotropic microlayers, when the birefringent microlayers become birefringent birefringent, the layer-to-layer refractive index differences along the y- and z-directions are all zero Can not. As a result, it can be seen that for highly-sloped light propagating along p-polarized light propagating in a reference plane including the y-axis (i.e., the pass axis of the polarizer) and the z- The residual reflectance for light propagating at high tilt angles with respect to the optical axis of the optical axis (if used in the display) and the tinted color.

nz이다.) 이러한 유형의 복굴절을 갖는 재료는 일축 복굴절성인 것으로 칭해진다. 복굴절성 미세층들이 등방성 미세층들과 교번하는 반사 편광기에서, 복굴절성 미세층들이 일축 복굴절성이 되면 y-방향 및 z-방향을 따른 층들간 굴절률 차이들은 모두 0이거나, 또는 실질적으로 0일 수 있고, 반면 x-방향을 따른 굴절률 차이는 0이 아니며 크기가 크다. 이로 인해 높은 경사 각도들에서 현저한 반사율은 거의 없거나 전혀 없고, 필름이 디스플레이의 반사 편광기로서 사용되는 경우에 이러한 각도들에 지각색은 거의 없거나 전혀 없다.In a second known technique, the film or web advances through a stretching device specifically designed to allow the web or film to fully relax in the down-web direction during the orientation process. For example, in some embodiments, the elongating device utilizes sets of clips moving along parabolic-shaped rails. See, for example, U.S. Patent No. 6,949,212 (Merrill et al.). By relaxing the film in the down-web direction (as well as in the thickness direction), the layers in the film that become birefringent under the conditions of stretching typically produce only two different refractive indices along the three main directions of the film . In other words, for this birefringent layer, the refractive index along the z-direction is equal to or substantially the same as the refractive index along the y-direction, but these refractive indices are substantially different from the refractive index along the x-direction (stretching direction) . Using nx, ny, nz notation, ny = nz, but nx ≠ ny and nx ≠ nz. (In some cases, ny and nz may not be exactly the same, but as discussed below, the difference is very small.

nz.) Materials of this type of birefringence are referred to as uniaxial birefringence. In a reflective polarizer where the birefringent microlayers alternate with isotropic microlayers, when the birefringent microlayers are uniaxially birefringent, the refractive index differences between the layers along the y- and z-directions are all zero or substantially zero While the refractive index difference along the x-direction is not zero and is large. This results in little or no significant reflectivity at high tilt angles and little or no tinting at these angles when the film is used as a reflective polarizer of the display.

Thus, with respect to off-axis color in a display, a multilayer reflective polarizer produced using a multilayer reflective polarizer, such as a parabolic stretcher, wherein the birefringent microlayers are uniaxial birefringent, is characterized in that the birefringent microlayers are polarizers that are birefringent, And has an inherent advantage over a polarizer manufactured using a tenter. However, in practice, the uniaxial birefringent polariser is more expensive to manufacture than the biaxial birefringent polariser if all other factors are the same, at least in part because the yield for the dedicated parabolic stretcher is substantially less than the yield for standard tenter .

The optical materials that can be used in the fabrication of the disclosed reflective polarizers can be selected from known materials, preferably transparent polymeric materials having material properties that permit co-extrusion of these materials at the same temperature and in a common feed block. In exemplary embodiments, layers of alternating thermoplastic polymers (ABABAB ...) are used, and under the conditions of stretching, one of the polymers is selected to be birefringent, while the other polymer is optically isotropic Is selected. Suitable polymers can be selected carefully, for example, from polyethylene naphthalate (PEN), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), copolymers thereof and combinations thereof. Other classes of polymers that exhibit birefringence and may be useful for this purpose are polystyrene (including syndiotactic polystyrene), polyamides (including nylon 6), and liquid crystal polymers.

With respect to the above discussion of uniaxial and zip birefringence and equations and inequalities involving nx, ny and nz, the present inventors have found that the exact equations between the two refractive indices can be difficult to achieve or measure, Differences recognize that they may not be distinguishable from exact equations. Thus, for purposes of this disclosure, the present inventors have found that when the refractive indices of a pair of materials are substantially equal, e.g., they differ by less than 0.05, the refractive indices of the remaining pairs of materials are not substantially equal, , If they differ by more than 0.05 - the material is considered to be uniaxial birefringence. Likewise, if the principal indices of refraction of each and every pair of materials are not substantially equal-for example, they differ by at least 0.05, the material is considered to be birefringent.

Typically, and in particular with respect to multilayer optical film reflective polarizers, the biaxially birefringent layer of such a polarizer is, for example, ny - nz | ≥ 0.05, and | nx - ny | (Nx, ny, nz) satisfying the relation of > 0.06 or 0.08. In contrast, the uniaxially birefringent layer of such a polarizer can, for example, ny - nz | <0.05, and | nx - ny | (Nx, ny, nz) satisfying the relation of > 0.06 or 0.08.

Another design aspect of particular relevance to the present application is the number of separate stacks of microlayers present in the completed multilayer reflective polarizer, which is often related to whether or not layer multiplexer devices are used during the manufacture of the film. Reference is now made to Fig. 2, which schematically illustrates a single packet multilayer optical film constructed as a reflective polarizer 220 in describing this feature.

The multilayer optical film or polarizer 220 has two mutually opposed outer major surfaces 220a and 220b with a plurality of distinct polymer layers therebetween. Polymer materials and film making equipment that can be used to produce such films by coextrusion and stretching are known and are described, for example, in U.S. Patent Nos. 5,882,774 (Jonza et al.) And 6,783,349 (Neavin et al. See US 2011/0102891 (Derks et al.). Adjacent polymer layers have substantially different refractive indices along at least one of the x, y, or z major axes, so that some light is reflected at interfaces between the layers (depending on the propagation direction and polarization state of the light). Some of the polymer layers of the polariser 220 are sufficiently thin - referred to herein as " optically thin " - to reflect or refract light at a plurality of interfaces to impart desired reflectance or transmission properties to the multi- Undergoes destructive interference. These layers are referred to herein as microlayers and are labeled "A" and "B" in FIG. For reflective polarizers designed to reflect visible light, each microlayer typically has an optical thickness (i.e., a product of its physical thickness and its refractive index) that is less than about one micrometer. As known in the art, thicker layers such as skin layers or protective boundary layers (PBLs) may also be present in the polarizer as layer 222, as shown in FIG. 2 have. These " optically thick " layers have an optical thickness greater than 1 micrometer, and often greater than 1 micrometer, and are not considered microlayers. (Throughout this specification, where the term " thickness " is used without the word " optical ", its thickness refers to the physical thickness unless otherwise specified in the context).

Coherent grouping of the microlayers is referred to herein as a laminate or packet of microlayers or as a microlayer packet. As shown, polarizer 220 includes only one packet 224 of microlayers. The packet 224 has a (physical) thickness T ₁ and the polarizer 220 has a total thickness T ₂ as shown in the figure. Constructing the multilayer optical film with only one packet 224 of microlayers simplifies the fabrication process (if the number of desired microlayers is not excessive) and allows better control of the thickness and thickness profile of the microlayers, As a result, it is possible to better control the spectral reflectance and spectral transmittance characteristics of the reflective polarizer. In FIG. 2, pairs of adjacent microlayers form optical repeat units (ORUs) labeled ORU1 through ORU6, each ORU having an optical thickness (OT1, OT2, ...) equal to the sum of the optical thicknesses of its constituent microlayers. . Although only six ORUs (twelve microlayers) are shown, the reader will appreciate that a typical single-packet reflective polarizer will include more microlayers and ORUs to provide adequate reflectivity over the visible spectrum. For example, the total number of microlayers in a single packet reflective polarizer may be less than 500, or less than 400, or less than 350, or in the range of, for example, 200 to 500, or 200 to 400, or 200 to 350 or 225 to 325 Lt; / RTI &gt; The optical thickness of the ORU determines the wavelength at which the ORU represents the peak reflectance. The thickness of the ORUs in accordance with the preferred layer thickness profile in which the optical thickness of the ORUs progressively increases from one side of the packet (e.g., near the major surface 220a) to the opposite side of the packet (e.g., near the thick layer 222) Heavy control allows a packet of microlayers to provide a broad reflectivity over the range of visibility spectra and desired viewing angles if a sufficient number of ORUs are present in the packet.

An alternative approach to more easily achieving the desired optical performance goals is to design a multilayer optical film reflective polarizer to have more microlayers than can actually be incorporated into a single packet film. For this reason (or for other reasons), the use of at least one optically thick polymeric material that separates neighboring packets allows for the production of reflective polarizers in which the microlayers are divided or separated into two or more identifiable microlayer packets do. Such multipacket reflective polarizers can be manufactured in a variety of ways. For example, instead of using only one feed block, the reflective polarizer uses multiple feed blocks (corresponding to multiple packets) and combines the packets from these feed blocks while the polymeric materials are still liquid . See, for example, U.S. Patent Application Publication No. 2011/272849 (Neavin et al.). Alternatively, reflective polarizers can be fabricated using a layer multiplexer device, for example, as discussed in U.S. Patent No. 5,882,774 (Jonza et al.) Or 6,025,897 (Weber et al.). The layer multiplexer device may, for example, double or triple the number of microlayers and ORUs to produce a number of packets in the completed reflector polarizer (respectively) of 2x or 3x. In another approach, multiple packet reflective polarizers can be fabricated, for example, by laminating together two or more multilayer optical film reflective polarizers each made with a single feed block.

Disadvantages of multi-packet reflective polarizers tend to include (a) a relatively large physical total thickness which can be a significant disadvantage of some display applications, and (b) increased manufacturing cost due to multiple layers and hence higher material costs It is. (The disclosed reflective polarizers preferably have a thickness in the range of less than 50 micrometers, or less than 40 micrometers, or 20 or 25 micrometers to 50 micrometers, or 20 or 25 micrometers to 40 micrometers). However, a greater number of microlayers can be used, even when these polarizers are oriented using standard tenters, i.e., even when the birefringent microlayers in these reflective polarizers are birefringent, Achieve goals. This is because multiple packets can cause spectral flattening as described in patent application publication no. 2013/0063818 (Weber et al.), Resulting in a reduction in the amount of off-axis color. Single packet reflective polarizers can not take advantage of this spectrum planarization technique and have a smaller error range in terms of layer thickness variability.

When discussing the suitability of multi-layer optical films produced by co-extruding many layers of alternating polymeric materials through feedback / die and orienting the film in a stretching operation, and in visual display applications, One aspect of the film that is of substantial interest to the skilled artisan is the spatially uniform extent of the film produced. This aspect of the film is of interest because, in the intended application, it relates to how much the manufactured film can be used versus how much to discard. As a result, it affects manufacturing yield and manufacturing cost, and can also have size limits on how large pieces can be obtained or cut from a web of a given film to fit a large display system. In the case of optical films for use in LC displays, it is desirable that the degree of spatial uniformity is such that no film-related artifacts are observed in the displayed image.

The web of optical film 320 is schematically shown in Fig. The film 320 is produced on a film production line and comes from a tenter or other stretching device schematically depicted as element 309. The film 320 has a longitudinal or down-web orientation parallel to the y-axis as shown. The film 320 also has a transverse or cross-web orientation parallel to the x-axis as shown. The two opposing longitudinal edges 320a, 320b define the longitudinal boundaries of the film 320. During previous alignment steps, clip sets from the tenter or dedicated stretching device near these edges held the film, after which the film 320 was trimmed with edges 320a, 320b. Three film samples intended to be used as reflective polarizers in a display or other desired application, namely a film sample 321a near the film edge 320a, a film sample 321b near the film edge 320b, A film sample 321c of the center portion (with respect to the transverse direction) of the film sample 320 is shown in the figure. These film samples or pieces are cut from the larger web or film 320 using a knife, slitter, or other suitable cutting tool. As a reflective polarizer, each of the optical film 320 and film samples 321a, 321b, 321c has a minor axis parallel to the x-axis and a pass axis parallel to the y-axis.

In an ideal situation, the film samples 321a, 321b, 321c will all have the same optical properties and properties. However, in practice, the film 320 exhibits a certain amount of spatial variability. As a result, the layer thickness profile (and its corresponding spectral transmittance and reflectance properties) of the microlayer packet near the edge of the film 320 is determined by the layer thickness profile (and corresponding spectral transmittance and reflection characteristics) It is somewhat different. The amount of change in spectral characteristics between the center of the film and the edge is particularly important for the type of multi-layer optical film of interest in the present application, i.e. the birefringent microlayers in the film are birefringent birefringent, It has only one packet and is oriented using a standard tenter. This is because such films lack spectral planarization provided by multiple packets of different types of reflective polarizers. See, for example, patent application publication no. 2013/0063818 (Weber et al.).

In another part of the specification, the present inventors discuss optical properties such as transmission and reflection of certain polarizing films and laminates at specific angles and polarization states. Figure 4 is provided to help the reader understand some related orientations, planes and angles. In the figure, optical body 412-optical body may or may not be a multilayer optical film configured, for example, as a reflective polarizer (e.g., a TOP reflective polarizer), or such film may be an absorbing polarizer and / Which may or may not be laminated to the optical body, is shown in the context of the Cartesian xyz coordinate system. The optical body 412 as a polarizer has a passing axis 413 and a differential axis 414 corresponding to mutually perpendicular y-axis and x-axis, respectively. The z-axis corresponds to the thickness direction of the optical body 412, that is, to the axis perpendicular to the plane of the optical body 412. The light vertically incident on the optical body 412 propagates parallel to the z-axis and is characterized by a declination angle [theta] of zero. This light is substantially transmitted by the optical body 412 if the light has a linear polarization component parallel to the axis of travel 413 and is substantially blocked if the light has a linear polarization component parallel to the axis of shortness 414 Reflected in the case of a reflective polarizer, absorbed in the case of an absorbing polarizer).

As a result of the lack of alternative terms, " incident plane " means that both the surface normal direction and the light propagation direction are changed in both the case where light is incident on the film and the case where light is not incident on the film, Quot; reference plane " Likewise, " incident angle &quot; is used to refer to the angle between the surface normal direction (z-axis) and the light propagation direction, both for light incident on the film and light exiting the film, ([theta]).

Two reference planes of incidence 416 and 418 are included in the figure: reference plane 416 includes a minor axis 414 and a z-axis; The reference plane 418 includes a pass axis 413 and a z-axis. Two tilted incident rays 415 and 417 are shown in the figure. Light ray 415 is placed in plane 416 and light ray 417 is placed in plane 418. Beams 415 and 417 are obliquely incident because their directions of propagation form a positive angle (?) That is not zero for the z-axis, respectively. For each ray 415, 417, the polarization state of the ray can be decomposed into two orthogonal components represented by a pair of orthogonal twin-headed arrows in the figure: " p-polarized " and a component referred to as " s-polarized ", the polarization state of which is perpendicular to the plane of incidence. Looking at the drawing, it appears that the polarization direction of the p-polarized light with respect to the oblique ray 415 is not (and is not parallel) to the polarization direction of the p-polarized light with respect to the oblique ray 417. Similarly, the polarization direction of the s-polarized light for the oblique ray 415 is not (and is not parallel) to the polarization direction of the s-polarized light for the oblique ray 417. Polarized ("s-polar") component of light 415 while the p-polarized ("p-pol") component of light 415 is perpendicular to pass axis 413 and partially aligned with differential axis 414. [ quot; -pol &quot;) component is parallel to the passing axis 413. The p-pol component of ray 417 is perpendicular to the minor axis 414 and partially aligned with the pass axis 413 while the s-pol component of ray 417 is parallel to the minor axis 414. [ From this, it can be seen that, depending on the direction of incidence, the p-polarized light may be perpendicular to the pass axis in some cases and perpendicular to the minor axis in other cases, and the s- Parallel and in other cases parallel to the minor axis.

The two oblique rays 415 and 417 are special cases of the more general case of any tilted incident ray which is not parallel to plane 416 nor to plane 418, - You can have an incidence plane that is not parallel to the axis or y-axis. In order to fully characterize any such oblique ray, an additional angle, referred to as azimuth, is employed. The azimuth angle? Is an angle measured between the x-y plane, the x-axis (i.e., the minor axis) and the projection of such a ray in the x-y plane or between the x-axis (minor axis) and the incident plane of such a ray. The value of? = 0 corresponds to the plane 416, and the value of? = 90 corresponds to the plane 418.

Referring now to FIG. 5, it can be seen that the selected elements of the LC display system 500 are schematically illustrated. The selected elements shown are the same as or similar to the rear absorbing polarizer 558 (which may be the same or similar to the rear absorbing polarizer 158 of FIG. 1), (the reflective polarizer 142 of FIG. 1 or the reflective polarizer 220 of FIG. 2) Layer optical film reflective polarizer 520 and a light diffusing layer 525 disposed on the front major surface of the reflective polarizer 520. The multi- Other components that may be included in an LC display system, such as an LC panel, a front absorbance polarizer, and a backlight, are omitted from the drawings for simplicity. The optical film is generally placed in the x-y plane or parallel to the x-y plane. A first user or observer 508 is located in front of the system 500 and observes the display at normal incidence along the system optical axis parallel to the z-axis. A second user or observer 509 is also located in front of the system 500, observing the display at an oblique angle.

It is assumed that the back absorption polarizer 558 is any absorption polarizer known in the art as suitable for its LC display. Polarizer 558 has a through axis and a minor axis (not shown in FIG. 5), and the polarizer is oriented such that the through axis is parallel to the y-axis and the minor axis is parallel to the x-axis. In modern LC displays, the back absorption polarizer 558 is typically a high contrast polarizer with a contrast ratio of more than 1000. In this regard, the contrast of a polarizer for the purposes of this specification, unless otherwise specified, refers to a light incident vertically on the polarizer and whose wavelength is in the visible spectrum or within any other useful wavelength range for the polarizer, Quot; refers to the ratio of the transmittance of the polarizer to the transmitted state polarized light versus the transmittance of the polarizer to the blocked state polarized light. The absorption polarizer is sometimes referred to as having a high contrast in the case where the contrast is 1000 or more, or 10,000 or more. Currently available absorption polarizers can have a contrast ranging, for example, from 1000 to 100,000, or from 2,000 to 10,000.

The reflective polarizer 520 is assumed to be a TOP reflective polarizer as described above. Figure 5 shows a polarizer 520 in a stand-alone configuration, in accordance with popular belief that TOP reflective polarizers are not suitable for on-glass construction due to excessive off-axis color of the polarizer. Thus, the reflective polarizer 520 is separated from the absorbing polarizer 558 by an air gap 505. The reflective polarizer 520 is also provided with a light diffusing layer 525 on one major surface thereof which is disposed between the reflective polarizer 520 and the absorbing polarizer 558. The light diffusing layer 525 scatters light into a distribution or cone of angles, as shown by incident light 506 and scattered light rays 507. The scattering effectively mixes the rays propagating in different directions through the reflective polarizer 520 to reduce or eliminate the color associated with the reflective polarizer 520. The diffusion layer 525 is assumed to have a relatively high turbidity, for example, greater than 40% as measured using a haze-guard plus turbidity meter. The diffusing layer 525 can be any known type or design and can include, for example, glass or ceramic beads or other particles contained in a matrix of different refractive indices, or it can comprise glass or ceramic beads or other particles in a polymer / air or polymer / polymer interface A textured surface, a faceted surface, or otherwise a non-planar major surface.

As already mentioned, the inventors have found, through investigation and testing, that, in contrast to the dominant view, a properly designed and oriented TOP reflective polarizer is laminated in an on-glass configuration, i. E., In a high contrast back absorption polarizer, and And can provide acceptable optical performance without a diffusion layer or structure therebetween. (However, in some cases, it may include a diffusion layer or structure having a relatively low turbidity, such as less than 30%, or less than 20%, or less than 10% turbidity). Two examples of the on-glass configuration are shown in Figs. 6 and 7. Fig.

6, a laminate 630 or an optical body is shown wherein a multilayer optical film reflective polarizer 620 is attached to a back absorbance polarizer 658 by a transparent adhesive layer 626. As shown in FIG. The reflective polarizer 620, the back absorbing polarizer 658 and the adhesive layer 626 are all coextensive with each other and there is no air gap between the reflective polarizer 620 and the absorbing polarizer 658. The observer side of the laminate 630 is in the positive z direction and therefore the back absorbance polarizer 658 can be considered to be in front of the reflective polarizer 620. [ The reflective polarizer 620 may be the same or similar to the reflective polarizer 520 described above. Indeed, in the following description, it is assumed that the reflective polarizer 620 is a TOP reflective polarizer. The TOP reflective polarizer 620 may be the center portion of the reflective polarizer web (e.g., see film sample 321c in FIG. 3), or may be an edge portion (e.g., see film samples 321a and 321b).

The TOP reflective polarizer 620 has a passing axis 613a that is generally parallel to the y-axis and a minor axis 614a that is generally parallel to the x-axis. The number of ORUs in a single microlayer packet and the thickness profile of these ORUs have a high transmittance for a vertically incident visible light polarized parallel to the pass axis 613a and a high transmittance for a vertically incident visible light polarized parallel to the minor axis 614a (And this is because the transmittance + reflectivity for these low-absorbent multilayer optical films is equal to about 100%) for the light rays and provides them to the reflective polarizer 620. For example, the transmittance of the normal incidence visible light polarized parallel to the passing axis 613a may be 60% or more, or 70% or more, or 80% or more when averaged over the visible wavelength range, The transmittance of the normal incidence visible light polarized parallel to the light source 614a may be less than 30%, or less than 20%, or less than 10% when averaged over the visible wavelength range. The optical performance of the TOP reflective polarizer 620 for the oblique p-polarized light incident on the reference plane including the z-axis and the passing axis 613a is inevitable due to the biaxial birefringent properties of the birefringent microlayers of the film Is influenced by refractive index mismatch between the layers. For this oblique light at an incident angle of incidence of 60 degrees, the transmissivity of the reflective polarizer 620 (alone, in isolation from any absorption polarizer) is from 70% to 90% for at least some wavelengths from 450 nm to 700 nm, Or from 70% to 85%; In some cases, the transmittance for this oblique light may be less than 90% over the entire wavelength range of 400 nm to 500 nm.

The TOP reflective polarizer 620 may have a total thickness of less than 50 micrometers or less than 40 micrometers, or may have a total thickness ranging from 20 micrometers to 50 micrometers, or from 20 micrometers to 40 micrometers, or from 25 micrometers to 40 micrometers Lt; / RTI &gt; The layer thickness profile of the ORUs in the microlayer packet of the polariser 620 is such that the color shift of transmitted white light from normal incidence to an angle of inclination of 80 degrees and to any viewing angle including it is not appropriate , Which is further described below. Particularly, the color shift of such light is changed from the first CIE chromaticity (a *, b *) coordinates at normal incidence to the second CIE chromaticity (a *, b *) coordinates at any angle from θ = 80 degrees (? A *) ^ 2 + (? B *) ^ 2) is preferably less than 3.5, more preferably less than 2.5, most preferably less than 2.0.

The rear absorbing polarizer 658 having the passing axis 613b and the minor axis 614b may be the same as or similar to the rear absorbing polarizer 558 described above. In fact, it is assumed that the absorption polarizer 658 is a high contrast absorption polarizer. The absorbing polarizer 658 is oriented with respect to the reflective polarizer 620 such that the passing axes 613a and 613b are substantially aligned and the minor axes 614a and 614b are also substantially aligned. For example, two such substantially aligned axes may be characterized by an angular deviation of less than one degree or less than 0.1 degrees.

The transparent adhesive layer 626 may be any suitable optical adhesive, such as any optically transparent adhesive products available from 3M Company, St. Paul, MN, USA. The refractive index of the adhesive layer 626 is preferably reasonably close to the refractive index of the outer surface of the absorbing polariser 658 and the outer surface of the reflective polarizer 620 so that the Fresnel Thereby avoiding Fresnel reflections. The adhesive layer 626 preferably provides a permanent bond between the absorbing polarizer 658 and the reflective polarizer 620.

The laminate 630 may be (essentially) consisted solely of, or consist essentially of, a reflective polarizer 620, an absorbing polarizer 658, and an adhesive layer 626. In some embodiments, the laminate 630 and each of these three components may be made from any of a number of different refractive index beads or other particles, or any significantly discernible light-diffusing layer, such as a textured or other non-planar major surface, Do not include structures. Thus, the laminate 630 may be free of any such light diffusing layer or structure. When the laminate 630 comprises such a diffusion layer or structure it is placed between the reflective polarizer 620 and the absorbing polarizer 658 or on the side of the reflective polarizer 620 opposite the absorbing polarizer 658, Or in the reflective polarizer 620, or in the absorption polarizer 658. [ The foregoing statements are made with the recognition that even ideal flat optical films and layers with superior optical transparency may exhibit a fine but measurable amount of optical scattering or diffusion. Thus, for the sake of clarity, the inventors can set a minimum threshold that, from a practical point of view, and for purposes of this specification, a layer or layer of interest can be considered to have no light diffusion. The inventors have determined that this minimum optical diffusion threshold can be reduced by 5% when measured using a haze-guard plus turbidity meter from Bowei-Gardner, Silver Springs, MD, according to a suitable procedure as described in ASTM D1003, Or 4%, or 3%, or 2% or 1%.

Optical films are often sold and / or shipped with a temporary polymer release liner on both sides to protect the major surfaces of the film from scratches or other damage. This release liner can be easily removed from the product by peeling. Release liners may include dyes, pigments, or other agents including light diffusers, so that they can be easily seen or detected by the user. This temporary release liner may also be applied to the outer surface of the laminate 630. [ However, these release liners can be distinguished from the laminate 630 and need not be considered part of the laminate 630. Thus, as long as these release liners are present on the laminate 630 (or on other laminates disclosed herein including the laminate 730 below) and the laminate has substantial light diffusing properties, any significant light- Or that it does not contain a structure.

In some cases, however, it may be desirable to include one or more suitable diffusion layers or structures between the reflective polarizer 620 and the absorption polarizer 658, and such suitable diffusion layers or structures may be preferred, It should be noted that the reader has a certain amount of turbidity that is larger than the diffusion threshold, but still smaller than the turbidity diffusers typically found in stand-alone configurations such as in FIG. For example, a diffusion layer or structure may be included between the TOP reflective polarizer 620 and the high contrast absorbing polarizer 658 having a relatively low turbidity, such as less than 30%, or less than 20%, or less than 10% turbidity .

The microlayers and ORUs in the microlayer packet of the disclosed TOP reflective polarizer have physical thicknesses, optical thicknesses, or both, that are carefully adjusted and properly oriented, which can be applied to the reflective polarizer over the visible wavelength range of interest and For both normal incidence and highly inclined incidence, it is desirable to have a low transmittance (high reflectance) for interception state polarization and a high transmittance (low reflectance) for pass state polarization, ) - providing a thickness profile that provides a low transmitted color, where [phi] is in the range of 15 to 45 degrees. The unwanted color at high tilt angles in the passing state of the polariser (closely related to the white state of the display where the TOP reflective polarizer is located) causes the thicker ORUs in the microlayer packets to be transmitted to a higher contrast absorbing polarizer than the thinner ORUs By placing them closer together and following the inherent bandwidth-based boxcar mean of the physical thickness profile (IB-flattened thickness profile), the presence of ORU 450, ORU 600, and ORU 645 And the IB-planarized thickness profile is calculated from a first average slope ranging from ORU 450 to ORU 600 and a second average slope ranging from ORU 600 to ORU 645 And ensuring that the ratio of the second mean slope to the first mean slope is less than or equal to 1.8. By satisfying this condition, the TOP reflective polarizer, and the laminate to which it is part, is capable of: - in white light passing through it at highly inclined angles - in the case of a display comprising such a polarizer or laminate, Can be given a predetermined amount of color that is sufficiently close to the intermediate whiteness or the target whiteness to be acceptable.

Other laminate 730 or optics are shown in FIG. The laminate 730 may be the same as or similar to the laminate 630 described above except that two additional layers are added. Thus, the laminate 730 includes a high contrast back absorbing polarizer 758, a TOP reflective polarizer 720, and an adhesive layer 726 that bonds the absorbing polarizer 758 to the reflective polarizer 720. These elements may be the same or similar to the corresponding elements of the laminate 630 and they may be the same or similar to the laminate 630 except that the front side of the structure 730 ' To form an optical body or structure 730 '. In particular, the front major surface of the high contrast back absorption polariser 758 is bonded to the glass layer 754 through an adhesive layer 728. The adhesive layer 728 may be the same or similar to the adhesive layer 726. The glass layer may be the rear or back panel plate of the liquid crystal panel, such as the panel plate 154b of the LC panel 150 described above.

The laminate 730 can be made essentially (or only) with elements 720, 726, 758, 728 and 754 as described above. Similar to the laminate 630, each of the laminate 730 and its components may have beads or other particles of different refractive index, or any significantly discernible light-diffusing layer or structure, such as a textured or other non- . Thus, the laminate 730 may be free of any such light diffusing layer or structure. When the laminate 730 comprises such a diffusing layer or structure it is placed between the reflective polarizer 720 and the absorbing polarizer 758 or on the side of the reflective polarizer 720 opposite the absorbing polarizer 758, Or in the reflective polarizer 720, or in the absorption polarizer 758. [ As discussed above, even ideal flat optical films and layers with superior optical clarity can exhibit measurable optical scattering and we believe that the layer or structure of interest has no light diffusion for the purposes of this disclosure A minimum threshold value that can be considered can be set. Appropriate thresholds are given above. Also, in some instances, one or more diffusion layers or structures (not shown) may be disposed between the reflective polarizer 720 and the absorbing polarizer 758, having a small but significant amount of turbidity, e.g., less than 30%, or less than 20% May be desirable.

The layer thickness profile used in the disclosed TOP reflective polarizers, such as the TOP reflective polarizers of the laminates of Figs. 6 and 7, assures some additional discussion. As already mentioned, the microlayers of the microlayer packet are composed of Optical Repeat Units (ORUs), and for light over the entire visible spectrum, the optical thicknesses of the ORUs (and microlayers) And to provide a high broadband reflectivity for the light of the blocked polarized light and a high broadband transmittance (low reflectivity) for the light of the pass polarized light both over the desired range of oblique incidence angles and directions. This is accomplished by adjusting the thickness profile of the ORUs to be a monotonic or nearly monotonic function along the thickness direction (z-axis) of the film, where thinner ORUs are generally referred to as one side of the packet , And the thicker ORUs are generally located on the opposite side of the packet (referred to herein as the thick side).

In order to reduce the undesired perceived off-axis transmitted color of the disclosed films, (a) the thick side of the microlayer packet faces the absorption polarizer (and accordingly also the observer and the LC panel) (B) the IB-planarized thickness profile of the microlayer packet is transmitted from the ORU 450 to the ORU 600 (as shown in FIG. 4), so that the thin side of the packet faces away from the absorption polarizer (and hence toward the backlight of the display system) ) And a second mean slope ranging from the ORU 600 to the ORU 645, and ensuring that the ratio of the second mean slope to the first mean slope is less than or equal to 1.8 It is useful to adjust the ORU thickness profile to vary smoothly. By satisfying this condition, the TOP reflective polarizer, and the laminate to which it is part, is capable of: - in white light passing through it at highly inclined angles - in the case of a display comprising such a polarizer or laminate, Can be given a predetermined amount of color that is sufficiently close to the intermediate whiteness or the target whiteness to be acceptable.

The above discussion of the ORU thickness profile and the properties thereof that the present inventors have found to be adjustable to maintain the color effects of the TOP reflective polarizer and the laminate containing it at an acceptable low level is now described in greater detail Will be described with the help of some embodiments as well as some embodiments. The present inventors begin a more detailed discussion of the simplified ORU physical thickness profile, with reference to Figures 8A and 8B. The simplified thickness profile makes it easier for the individual ORUs to flatten the thickness profile using boxcar averaging and resonant wavelengths for the boxcar averaged (planarized) thickness profile in a given optical geometry I can explain it. Thereafter, many TOP reflective polarizer embodiments, and their modeled color related performance at highly inclined angles, are discussed and compared in connection with Figs. 9 to 30C. Finally, an exemplary TOP reflective polarizer is discussed in relation to Figures 31-32C, and two comparative TOP reflective polarizers are discussed in connection with Figures 33-36. Unless otherwise specified, all embodiments include an ORU physical thickness profile with a gradient providing a broad band reflectance for vertically incident light polarized along the blocking axis, the ORUs having a resonant wavelength as a function of physical thickness profile and optical geometry shape Respectively.

Figures 8A and 8B illustrate, in a simplified fashion, the concepts of the ORU physical thickness profile, the planarized physical thickness profile by boxcar averaging (e.g., intrinsic bandwidth (IB) based boxcar averaging), and the oblique angle resonant wavelengths. In Figure 8A, the physical thickness profile of the hypothetical TOP reflective polarizer is presented as a graph plotting the ORU thickness versus the number of ORUs. For generalization, numerical indications are not provided on the vertical axis of the graph, but the reader will appreciate that the thickness increases linearly in the direction of the axis arrow. The horizontal axis is simply a count of the number of ORUs starting at the first end of the microlayer packet. (Thus, the horizontal axis is also closely related to the physical location or depth in the reflective polarizing film relative to the first end of the packet.) Examination of that axis reveals that the hypothetical polarizer has exactly 15 ORUs. Each ORU may be composed of two adjacent microlayers, for example, as shown in Fig. 2 above. Point P15 represents the physical thickness of the first ORU, point P2 represents the physical thickness of the second ORU, and so on, and point P15 represents the physical thickness of the 15th (and last) Indicates the physical thickness of the ORU. The collection of points P1 to P15 is an ORU physical thickness profile of the packets of the microlayers of the reflective polarizer. As shown, this thickness profile monotonically increases and is substantially linear as a function of the number of ORUs. ORUs close to the 15th (last) ORU have an average physical thickness that is greater than the average physical thickness of the ORUs proximate to the first ORU.

For any given optical geometry, each ORU may have a full-width-at-half-maximum, which refers to (1) the peak or maximum reflectivity, and (2) To produce a reflectance spectrum characterized by a width or width of the spectrum). The set of spectral reflectances of all the ORUs in the microlayer packet then substantially yields the reflectivity of the TOP reflective polarizer as a whole. The peak reflectance of a given ORU occurs at a wavelength referred to as the resonant wavelength (for that ORU); The peak reflectance and hence the resonant wavelength change as a function of the optical geometry. For normal incident light, the resonant wavelength is equal to half the optical thickness of the ORU, where the optical thickness is different from the physical thickness as detailed above. At tilt angles, the resonant wavelength is smaller than the resonant wavelength at normal incidence, and it is also different for s-polarized light and p-polarized light in general. The intrinsic bandwidth of the ORU reflectance spectrum is affected to some extent by the optical geometry but is also influenced by other factors such as the refractive indices of the microlayers in the packet and the refractive index differences between such microlayers.

The fact that each ORU in a packet has a reflectivity with a non-zero unique bandwidth is due to the fact that the reflectivity of the reflective polarizer as a whole at a given given wavelength (and for a particular optical geometry) As well as that the resonant wavelengths are also due to neighboring ORUs close to the specific wavelength (with respect to the intrinsic bandwidths of the ORU reflection spectra). For example, it is assumed that the ORU represented by point P10 has exactly a resonant wavelength of lambda 10 in a given optical geometry, and then the reflectance of the reflective polarizer (and packet) as a whole at its wavelength? 10 (and in a given optical geometry) , Such latter reflectivity may be due not only to the ORU at point P10, but also to some of its nearest neighbor ORUs on both sides, as indicated by group G10 in Figure 8A. In the case of the reflectance at the wavelength corresponding to the resonance wavelength of the ORU at or near one end of the two ends of the microlayer packet, such as the ORU for point P1 in Fig. 8a or the ORU for point P15, Neighboring ORUs may exist only on one side of the ORU, resulting in biased or unbalanced ORU groupings such as group G1 and group G15 in FIG. 8A.

The above-described phenomenon of overlapping reflectance bands for neighboring ORUs is achieved by averaging the thickness of the ORU, if any, and the thickness of its neighboring ORUs on each side of the ORU in each of the fifteen ORUs, To define the ORU thickness profile. This technique is referred to as boxcar averaging. The actual number of neighboring ORUs contained on each side of the ORU will depend on the inherent bandwidths of the ORUs in the microlayer packet and other factors, but for the purposes of this simplified example, Contains two ORUs (as long as they exist). The result of this intrinsic bandwidth (IB) based boxcar averaging is illustrated in FIG. 8A by the small open circle marks provided in each of the fifteen ORUs, A1, A2, A3, etc., etc. through A15. As long as the original ORU thickness profile as denoted by points P1 to P15 is strictly linear, due to the symmetry nature of the boxcar averaging for such ORUs, marks A3 to A13 will also be linear and their respective points P3 To P13. However, for ORUs at and near the ends of the packet, the IB-flattened thickness profile is not uniform due to the asymmetric nature of the boxcar averaging for such ORUs, so that their respective points P1, P2, P14, P15 And deviates from the original thickness profile, as shown by the mismatch of open circles A1, A2, A14, A15.

Following these calculations, the IB-planarized thickness profile and the sufficiently tilted optical geometry are then selected to be p-polarized light that is incident on the xz plane (see, e.g., Fig. 4 above) at a shear angle [theta] And calculates the resonance wavelength for each of the fifteen ORUs based on the resonance frequency. This calculation is based on the refractive index values nx, ny, nz (wavelength dependent) for each of the microlayers in the IB-planarized thickness profile and other parameters, e.g., ORUs (see discussion of FIG. 2 above) A Berriman 4x4 matrix multilayer optical response calculation engine utilizing optical geometry as inputs may be employed. With this information, the resonant wavelength in a particular tilted angular geometry can be calculated for each of the fifteen ORUs. The result is plotted in FIG. 8B as a graph of resonant wavelength vs. ORU number. The Berriman method can also be used to calculate the spectral reflectance and spectral transmittance of such polarizers laminated to a TOP reflective polarizer and a high contrast absorptive polarizer.

For generalization, numerical indications are not provided on the vertical axis of the graph, but the reader will appreciate that the resonant wavelength increases linearly in the direction of the axis arrow. The horizontal axis is simply a count of the number of ORUs starting at the first end of the microlayer packet, as in the graph of Figure 8A. The x-shaped points labeled W1, W2, W3, etc. to W15 represent the resonant wavelengths calculated in each of the ORUs.

Now that the above calculations have been carried out, it is determined whether the (virtual simulated) TOP reflective polarizer meets the conditions to promote low saturation in the transmission of the reflective polarizer and of the laminate of the high contrast absorption polarizer and the reflective polarizer I am ready to participate in the analysis to do so. As part of this analysis, it is determined whether any of the ORUs in the microlayer packet satisfy both of the following conditions: a specific oblique optical geometry (p-polarized light incident at &amp;thetas; = 80 degrees in the xz plane ) And the resonant wavelength for the IB-planarized thickness profile is 450 nm or more; All ORUs placed on the side of the ORU containing the first ORU have resonant wavelengths below 450 nm (under the same conditions). If so, this ORU is referred to as ORU 450. (Preferably, for an IB-planarized thickness profile in a particular tilted optical geometry, the resonant wavelength of the ORU 450 is less than 455 nm.) Similarly, any of the ORUs in the microlayer packet may be (P-polarized light incident at &amp;thetas; = 80 degrees in the xz plane) and the resonant wavelength for the IB-planarized thickness profile is at least 600 nm ; All ORUs placed on the side of the ORU containing the first ORU have resonant wavelengths below 600 nm (under the same conditions). If so, this ORU is referred to as ORU 600. (Preferably, for an IB-planarized thickness profile in a particular tilted optical geometry, the resonant wavelength of ORU 600 is less than 605 nm.) In a similar manner, any of the ORUs in the microlayer packet : The resonant wavelength for a particular tilted optical geometry (p-polarized light incident at? = 80 degrees in the xz plane) and for the IB-planarized thickness profile is greater than or equal to 645 nm ego; All ORUs placed on the side of the ORU containing the first ORU have resonant wavelengths below 645 nm (under the same conditions). If so, this ORU is referred to as ORU 645. (Preferably, for IB-planarized thickness profiles in a particular tilted optical geometry, the resonant wavelength of ORU 645 is less than 650 nm.) ORU 400, ORU 600, ORU 645 Is defined in a highly graded optical geometry, meaning that their properties for perpendicular incident light will be substantially different from their properties in the oblique geometry. For example, the ORU 645 will likely have a resonant wavelength for vertical incident light that is within the near infrared portion of the electromagnetic spectrum.

Planarized thickness profile (e.g., see points A 1 to A 15 in FIG. 8A) when the TOP reflective polarizer includes all three of ORU 400, ORU 600, and ORU 645, and In particular, an additional analysis of the average slope of the profile is performed. The first average slope of the IB-flattened thickness profile over the short wavelength range, ORU 400 to ORU 600, is compared with the first average slope of the same profile across ORU 600 to ORU 645 over a longer wavelength range, Compare with the second mean slope. (If reflective polarizers are oriented such that the ends of the microlayer packets with thicker ORUs are adjacent or facing the absorptive polarizer), for a laminate of a polarizer and a high contrast absorptive polarizer, and for a white state of a display comprising a laminate, The low transmitted color for the polarizer is promoted when the ratio of the second mean slope to the first mean slope is less than 1.8.

Although such an analysis utilizes resonant wavelengths as calculated for p-polarized light incident on a particular highly-graded optical geometry, i.e., the angle of declination (?) = 80 degrees xz plane, the low color output ) Is never limited to its geometric shape. In other words, when the reflective polarizer and the laminate to which it is part are adjusted as described in the above analysis, it is preferred that the angle of inclination (in the range of 0 to 90 degrees) Low color transmission is achieved in other highly inclined geometries, including the mid-azimuthal angles phi, and for other polarization states.

9 and related Figures 10a to 17c demonstrate the application of these principles to a number of related (modeled) embodiments of TOP reflective polarizers and their laminates with high contrast absorption polarizers. The transmission and reflection spectra of the reflective polarizer were calculated using a Berriman 4 × 4 matrix multilayer optical response calculation engine. The input parameters for the calculations included the layer thickness profile of the ORUs and the wavelength dependent refractive index values for the birefringent microlayers and isotropic microlayers that make up the microlayer packets and ORUs.

In these embodiments, the TOP reflective polarizer has exactly 152 ORUs. Each ORU contains only two microlayers, one of which is biaxially birefringent and the other is isotropic, where the f-ratio is 0.5. The birefringent microlayers are assigned a refractive index set (nx, ny, nz) based on measured data for uniaxially stretched LmPEN (Low Melt Point PEN). With respect to the composition of LmPEN, the diol is 100% ethylene glycol while the diacid is 10 mol% teraphthalic acid and 90 mol% naphthalene dicarboxylic acid. The isotropic microlayers are assigned an isotropic refractive index (Niso) based on measured data for amorphous blends of 58% and 42% weight fractions of PETg GN071 (Eastman Chemicals, Knoxville, TN, USA) and LmPEN, respectively. The refractive indices of these materials as used in this computational modeling are shown in Table 1:

[Table 1]

The examination of the table reveals that nx is larger than Niso, providing a large refractive index difference for the fields along the x-axis. The value of ny is approximately equal to Niso. The value of nz is smaller than Niso, thus providing a refractive index difference for p-polarized light for non-normal incidence angles. Based on the teachings of the SCIENCE literature, referenced below, the combination of birefringent and isotropic refractive indices shown in Table 1 can be used for both an increasing angle of incidence (?) And for both s-polarized light and p- An increase in the interfacial reflectance and an increase in the reflection band power.

In FIG. 9, there is a graph of eight different but related ORU physical thickness profiles 961, 962, 963, 964, 965, 966, 967, 968, any of which can easily be employed in a TOP reflective polarizer have. The thickness profile 961 is of a linear shape, i.e., a constant slope, from the first ORU (# 1) with a physical thickness of about 120 nm to the last ORU (# 152) with a physical thickness of about 265 nm. The other thickness profiles 962 to 968 are the same as the thickness profile 961 in ORU # 1 to ORU # 105, but then in ORU # 105 they are a step change in slope of the thickness profile from ORU # 105 to ORU # step-change. The step change in slope is the smallest for profile 962 and largest for profile 968, as shown in the figure.

Then, each of these ORU thickness profiles, from the ORU thickness profile,

박스카 평균의 목적을 위해, 모델링된 굴절률들에 대한 ORU 반사 대역들의 고유 대역폭을 고려하기 위해, 당해 ORU의 각각의 측부 상에 포함하는 ORU들의 수가 (존재하는 경우) 10인 IB-평탄화된 두께 프로파일, 및

For purposes of boxcar averaging, IB-flattened thicknesses (where present), where the number of ORUs contained on each side of the ORU, if present, is taken into account to account for the intrinsic bandwidth of the ORU reflection bands for the modeled refractive indexes Profile, and

80도의 편각(θ)으로 x-z 평면에 입사되는 p-편광된 광의 고도로 경사진 광학 기하형상에 대해, 각각의 ORU에서의 IB-평탄화된 두께 프로파일의 공진 파장을 계산하고; 이어서

Calculating a resonant wavelength of the IB-planarized thickness profile at each ORU, for a highly-sloped optical geometry of p-polarized light incident on the xz plane at an angle of inclination of 80 degrees; next

미세층 패킷이 전술된 바와 같은 ORU(450), ORU(600), 및 ORU(645)를 포함하는지 여부를 결정하고; 만일 그렇다면,

Determine whether the microlayer packet includes ORU 450, ORU 600, and ORU 645 as described above; if so,

ORU(450)으로부터 ORU(600)으로의 IB-평탄화된 두께 프로파일의 제1 평균 기울기를 계산하고, ORU(600)으로부터 ORU(645)로의 IB-평탄화된 두께 프로파일의 제2 평균 기울기를 계산하고;

Calculate a first mean slope of the IB-planarized thickness profile from the ORU 450 to the ORU 600, calculate a second mean slope of the IB-planarized thickness profile from the ORU 600 to the ORU 645 ;

제1 평균 기울기에 대한 제2 평균 기울기의 비("기울기 비")를 계산함으로써, 전술된 바와 같이 분석된다.

By calculating the ratio of the second mean slope to the first mean slope (" slope ratio &quot;).

미세층 패킷이 ORU(450), ORU(600), 또는 ORU(645) 중 어느 하나를 포함하지 않는 경우, 전술한 기울기 비는 정의되지 않음에 유의한다.

Note that if the microlayer packet does not include any of ORU 450, ORU 600, or ORU 645, the above-described slope ratio is undefined.

In addition, we also use the Berriman method to define the azimuth angles (?) Of 15, 25, 35, and 45 degrees by the range of the angle of inclination (?) Of 45 to 85 degrees in 5 degree increments For a range of highly graded optical geometries such as those described above, there is no air gap or diffusion material between the aligned absorbed polarizers with 10,000 contrast ratios and the modeled TOP reflective polarizer-there is no air gap or diffusion material between them, (And ORUs) are oriented such that the reflective polarizer is oriented closer to the absorption polarizer than the thinner microlayers (and ORUs). (Such angles are often sensitive to undesired color or color variations in the white state of standard display panels.) For each such geometry, e.g., (? = 50 degrees,? = 35 degrees) The model initiates the unpolarized input light beam in a particular direction toward the laminate, which is incident on the thinnest layer end of the microlayer packet, i.e., from air on ORU # 1. The spectral content of the input beam is modeled as a standard display white LED filtered through red, green, and blue filters, representing an LC display. The Berriman method then calculates the output beam as it is transmitted through the laminate (both the TOP reflective polarizer and the aligned high contrast absorption polarizer) and computes the spectral content of the output beam. Comparing the calculated output beam with the input beam yields a color response for the laminate in a particular geometry. Quantize the color response with respect to known CIE (L *, a *, b *) color coordinates. The general color response performance of the laminate (and reflective polarizer) can be evaluated by evaluating (a *, b *) values calculated over the modeled range of azimuth and declination angles.

Thus, in FIG. 10A, the composite graph includes a single horizontal axis representing the number of ORUs, a left-hand-side (LHS) vertical axis representing the ORU (physical) thickness in nanometers (nm) And a right-hand-side (RHS) vertical axis representing the resonance wavelength of the unit. The use of dual vertical axes allows plotting both the ORU thickness (using the LHS axis) and the resonant wavelength (using the RHS axis) for the number of ORUs on the same graph. Curves 961 and 961A are plotted against the LHS vertical axis and curve 961W is plotted against the RHS vertical axis.

Curve 961 is identical to the ORU physical thickness profile 961 of FIG. 9, with a constant slope from ORU # 1 to ORU # 152. (Indeed, when actual multilayer film samples are provided, the ORU physical thickness profile is typically measured using an ATOMIC Force Microscopy (AFM) system designed for multilayer polymer characterization and is obtained from the AFM Some averaging or planarization of the raw data may be required.)

Curve 961A is an intrinsic bandwidth (IB) based boxcar mean of curve 961. For any of ORU # 11 to ORU # 142, the corresponding point on the averaged or flattened curve 961A is the sum of the given ORU, 10 ORUs immediately adjacent to the given ORU on the left, and 10 ORUs immediately adjacent to the given ORU on the right Is derived by calculating the average thickness (from curve 961) for a group of ORUs consisting of 10 ORUs. Thus, the averages for these ORU # 11 through ORU # 142 are derived from the group of 21 ORUs. In the case of ORUs at or near the ends of the microlayer packet, i.e., ORU # 1 to ORU # 10 and ORU # 143 to ORU # 152, less than 21 ORUs are used for the group average, Is that for these ORUs less than 10 ORUs are available on the left or right side of a given ORU. ORUs per side (based on the intrinsic bandwidth of the resonant quarter-wave ORUs, among other things that influence the transmission characteristics of the microlayer thickness profile packets in the critical observer range of interest, The 21-ORU group) boxcar mean is appropriate and represents the reflection / transmission behavior of the microlayer thickness profile for the disclosed embodiments. The inherent bandwidth of ORUs with quarter wavelength microlayers, with refractive indices as shown in Table 1 above, is approximately 10%. This implies that, for any given wavelength, approximately 10 ORUs, which are thicker close neighbors of the central ORU, and 10 ORUs, which are their thinner neighboring neighbors, will participate in generating a reflection response at the given wavelength; Thus, the use of terms such as the 21-ORU boxcar mean reflector group is implied.

The IB-planarized thickness profile evaluated at any given ORU preferably contains substantially only such ORUs that consistently contribute to the reflectivity of the packet at the resonant wavelength of the given ORU. In embodiments of the primary interest in the immediate discussion, this means that the IB-flattened thickness profile includes ten nearest neighbor ORUs on each side of a given ORU. However, in other embodiments, the IB-planarized thickness profile can be used to determine the thickness of a given layer, for example, as a result of different intrinsic bandwidths, due to substantially different refractive indices and refractive index differences, And may include a predetermined number of nearest neighbor ORUs on each side of the ORU. In such cases, the predetermined number of ORUs (on each side of a given ORU) is less than 20, but may be 5 or more.

The floating values of the 21-ORU boxcar mean are calculated continuously starting from ORU # 11, to ORU # 142, near the thin end of the microlayer packet. Then, from ORU # 143 to the last ORU # 152 on the thick end of the packet, the group of ORUs in the boxcar mean is reduced from 20 to 11 because the number of ORUs available on the right is reduced. Each of these boxcar averaged ORU values represents a group of microlayers that consistently serves to produce a reflection band at a wavelength appropriate for its optical phase thickness, which is then used to determine the polarization state of the incident light, the refractive index of the external medium from which the incident light emerges, It depends on the azimuth and declination of incident light. A detailed discussion of these properties for multilayered stacks of biaxial materials can be found in " Giant Birefringent Optics in Multilayer Polymer Mirrors ", SCIENCE vol. 287, pp. 2451-2456 (March 31, 2000).

Curve 961W in FIG. 10A shows that for p-polarized light having a highly sloped optical geometry characterized by? = 80 degrees,? = 0 and with an xz plane as its plane of incidence, (In nanometers) of the group of reflectors. That is, any point on the curve 961W at a given ORU is the resonant wavelength for the IB-planarized thickness profile 961A at a given ORU and at a particular tilted optical geometry. The reference line? C at the critical wavelength is also plotted, wherein the critical wavelength is chosen to be 645 nm for the disclosed embodiments. Examination of the graph reveals that the curve 961W contains resonant wavelengths of 400 nm, 600 nm, and 645 nm. As a result, the IB-planarized thickness profile 961A includes ORU 400, ORU 600, and ORU 645.

FIG. 10B graphically shows the slope of the IB-flattened thickness profile 961A from FIG. 10A as a function of the resonant wavelength as defined by curve 961W. That is, instead of scaling the horizontal axis of FIG. 10b according to the number of ORUs, it is scaled according to the resonant wavelength of each of the ORUs (in a particular tilted optical geometry). The calculated slope is simply the same as the progression of the curve 961A of FIG. 10A. This calculated slope is shown as curve 961S in Figure 10b, which has a discontinuity at about 665 nm due to a sharp change in the slope of curve 961A near ORU # 141. In Fig. 10B, the reference line? C appears vertically at a critical angle of 645 nm. Extending from 600 nm to 645 nm (corresponding to ORU 645), extending from the first region 1001 extending from 450 nm (corresponding to ORU 450) to 600 nm (corresponding to ORU 600) Region 1002 is also included in FIG. 10B.

The slope ratio discussed above calculates the first average of the slope, i. E. The curve 961S, over the range of the first area 1001 and the slope over the range of the second area 1002 (curve 961S ) &Lt; / RTI &gt; In this embodiment, the examination of FIG. 10B reveals that the curve 961S is substantially flat over these two regions, so that the first and second averages are substantially identical. Thus, for this embodiment, the ratio of these averages (slope ratio) yields a value of 1.0.

Figure 10C graphically illustrates the color response for the embodiment of Figures 10A and 10B, as described in detail above, using (dimensionless) CIE a * and b * color coordinates. Briefly, using the Berriman method, a laminate of an aligned absorbed polariser with a contrast ratio of 10,000 and a modeled TOP reflective polarizer-no air gaps or diffusion material between them, and thicker microlayers (and ORUs) The color response of the reflective polarizer is oriented so that it is closer to the absorption polarizer than the thinner microlayers (and ORUs). The color response was calculated for highly inclined optical geometry for azimuths [theta] in the range of 45 to 85 degrees in 5 degree increments and azimuths [phi] of 15, 25, 35, and 45 degrees . The results are grouped in terms of azimuth, where the curve (φ 15) represents the color response for φ = 15 degrees over the range of declination and the curve (φ 25) represents the color response for φ = 25 degrees over the range of declination , Curve 35 represents the color response for &lt; RTI ID = 0.0 &gt;# 35 &lt; / RTI &gt; over a range of angle decays, and curve 45 represents the color response for 45 degrees over the range of declination angles. When comparing the (a *, b *) graphs presented herein, a reference circle labeled as C is provided to indicate the same scale. Unless otherwise noted, the circle C has a diameter of 3.0 (no upper limit) in all such graphs.

The same method as described above for the ORU physical thickness profile 961 and shown in Figures 10a, 10b, and 10c was then repeated for each of the other related ORU physical thickness profiles shown in Figure 9.

Thus, in the case of profile 962: Figure 11A shows that curve 962 is the same as profile 962, curve 962A is the IB-flattened thickness profile of curve 962, curve 962W is the IB- Is a resonance wavelength for an IB-planarized thickness profile in an oblique optical geometry, and a baseline (? C) is a composite graph representing a critical wavelength at 645 nm; Figure 11B graphically illustrates the slope of the IB-planarized thickness profile 962A as a function of the resonant wavelength as defined by curve 962W as curve 962S and the first region 1101 of 450 to 600 nm, A second region 1102 of 600 to 645 nm, and a reference line c at 645 nm; Figure 11C graphically illustrates the color response at the a *, b * color coordinates of the reflective polarizer-absorbing polarizer laminate, where the curves (15, 25, 35, 45) have a similar meaning to those of Figure 10c, And has a reference circle (C).

In the case of the profile 963: Fig. 12A shows that the curve 963 is the same as the profile 963, the curve 963A is the IB-flattened thickness profile of the curve 963 and the curve 963W is the IB- A resonance wavelength for an IB-planarized thickness profile in a geometric shape, and a baseline c is a composite graph representing a critical wavelength at 645 nm; Figure 12B graphically illustrates the slope of the IB-planarized thickness profile 963A as a function of the resonant wavelength as defined by curve 963W as curve 963S and the first region 1201 of 450 to 600 nm, A second region 1202 of 600 to 645 nm, and a reference line c at 645 nm; Figure 12c graphically illustrates the color response at the a *, b * color coordinates of the reflective polarizer-absorbing polarizer laminate, where the curves (15, 25, 35, 45) have similar meanings as those of Figure 10c, And has a reference circle (C).

13A shows that the curve 964 is identical to the profile 964 and the curve 964A is the IB-planarized thickness profile of the curve 964 and the curve 964W is the IB- A resonance wavelength for an IB-planarized thickness profile in a geometric shape, and a baseline c is a composite graph representing a critical wavelength at 645 nm; Figure 13B graphically illustrates the slope of the IB-planarized thickness profile 964A as a function of the resonant wavelength as defined by curve 964W as curve 964S and the first region 1301 of 450 to 600 nm, A second region 1302 of 600 to 645 nm, and a reference line c at 645 nm; Figure 13c graphically illustrates the color response at the a *, b * color coordinates of the reflective polarizer-absorbing polarizer laminate, where the curves 15, 25, 35, 45 have similar meanings as those of Figure 10c, And has a reference circle (C).

14A shows that the curve 965 is identical to the profile 965 and the curve 965A is the IB-planarized thickness profile of the curve 965 and the curve 965W is the IB- A resonance wavelength for an IB-planarized thickness profile in a geometric shape, and a baseline c is a composite graph representing a critical wavelength at 645 nm; 14B graphically illustrates the slope of the IB-planarized thickness profile 965A as a function of the resonant wavelength as defined by the curve 965W as curve 965S and the first region 1401 of 450 to 600 nm, A second region 1402 of 600 to 645 nm, and a reference line c at 645 nm; Figure 14C graphically illustrates the color response at the a *, b * color coordinates of the reflective polarizer-absorbing polarizer laminate, where the curves (15, 25, 35, 45) have similar meanings as those of Figure 10c, And has a reference circle (C).

In the case of profile 966: Figure 15A shows that curve 966 is identical to profile 966, curve 966A is the IB-flattened thickness profile of curve 966, curve 966W is the specific oblique optics A resonance wavelength for an IB-planarized thickness profile in a geometric shape, and a baseline c is a composite graph representing a critical wavelength at 645 nm; Figure 15B graphically illustrates the slope of the IB-planarized thickness profile 966A as a function of the resonant wavelength as defined by curve 966W as curve 966S and the first area 1501 of 450 to 600 nm, A second region 1502 of 600 to 645 nm, and a reference line? C at 645 nm; Figure 15c graphically illustrates the color response at the a *, b * color coordinates of the reflective polarizer-absorbing polarizer laminate, where the curves (15, 25, 35, 45) have similar meanings as those of Figure 10c, And has a reference circle (C).

In the case of profile 967: Figure 16A shows that curve 967 is identical to profile 967, curve 967A is the IB-flattened thickness profile of curve 967, curve 967W is the IB- A resonance wavelength for an IB-planarized thickness profile in a geometric shape, and a baseline c is a composite graph representing a critical wavelength at 645 nm; 16B graphically illustrates the slope of the IB-planarized thickness profile 967A as a function of the resonant wavelength as defined by the curve 967W as curve 967S and the first region 1601 of 450 to 600 nm, A second region 1602 of 600 to 645 nm, and a reference line c at 645 nm; Figure 16c graphically illustrates the color response at the a *, b * color coordinates of the reflective polarizer-absorbing polarizer laminate where the curves (15, 25, 35, 45) have similar meanings as those of Figure 10c, And has a reference circle (C).

17A shows that the curve 968 is identical to the profile 968 and the curve 968A is the IB-planarized thickness profile of the curve 968 and the curve 968W is the IB- A resonance wavelength for an IB-planarized thickness profile in a geometric shape, and a baseline c is a composite graph representing a critical wavelength at 645 nm; Figure 17B graphically illustrates the slope of the IB-planarized thickness profile 968A as a function of the resonant wavelength as defined by curve 968W as curve 968S and the first region 1701 of 450-600nm, A second region 1702 of 600 to 645 nm, and a reference line c at 645 nm; Figure 17C graphically illustrates the color response at the a *, b * color coordinates of the reflective polarizer-absorbing polarizer laminate, where the curves (φ 15, φ 25, φ 35, φ 45) have similar meanings as those of FIG. And has a reference circle (C).

The results of the slope ratios for the embodiments of Fig. 9 are summarized in Table 2, where the " slope ratio " refers to the slope of the slope of the profile of the IB-flattened thickness profile (600 to 645 nm) Refers to the value divided by the first average (450 to 600 nm).

[Table 2]

The color response of these embodiments to an observer at a highly inclined critical viewing angle is shown in Figures 10c, 11c, 12c, ... Is best evaluated by inspection of the color response curves in Figure 17c. Briefly summarized, the color traces of Figures 10c, 11c, 12c, and 13c (for ORU thickness profiles 961, 962, 963, 964, respectively) are within acceptable color limits; The color traces in Figures 14c, 15c, 16c, and 17c (for ORU thickness profiles 965, 966, 967, 968, respectively) are too wide, i.e. they produce an excessive amount of color.

18 and related Figures 19A-26C demonstrate the application of these same principles to other related (modeled) embodiments of TOP reflective polarizers and their laminates with high contrast absorption polarizers. Similar to the embodiments of FIG. 9, the TOP reflective polarizer embodiments of FIG. 18 also have exactly 152 ORUs, and each ORU has only two microlayers, the refractive indices as also provided in Table 1 above. Figure 18 shows eight different, but related, ORU physical thickness profiles 1861, 1862, 1863, 1864, 1865, 1866, 1867, 1868, any of which can be readily employed in a TOP reflective polarizer. The thickness profile 1861 is of a linear shape, i.e., a constant slope, from the first ORU (# 1) with a physical thickness of about 125 nm to the last ORU (# 152) with a physical thickness of about 275 nm. The other thickness profiles 1862 through 1868 are the same as the thickness profile 1861 in ORU # 1 through ORU # 125, but then in ORU # 125 they represent a step change in slope of the thickness profile from ORU # 125 to ORU # 152 Suffer. The step change in slope is smallest for profile 1862 and largest for profile 1868, as shown in the figure.

Each of these ORU thickness profiles was then analyzed in substantially the same manner as described above with respect to Figures 9-17C, and this analysis will not be repeated here to avoid unnecessary repetition.

19A shows that the curve 1861 is identical to the profile 1861 and the curve 1861A is the IB-flattened thickness profile of the curve 1861 and the curve 1861W is the IB- Is a resonance wavelength for an IB-planarized thickness profile in an oblique optical geometry, and a baseline (? C) is a composite graph representing a critical wavelength at 645 nm; Figure 19B graphically shows the slope of the IB-planarized thickness profile 1861A as a function of the resonant wavelength as defined by curve 1861W as curve 1861S and shows a first region 1901 of 450 to 600 nm, A second region 1902 of 600 to 645 nm, and a reference line c at 645 nm; Figure 19c graphically illustrates the color response at the a *, b * color coordinates of the reflective polarizer-absorbing polarizer laminate, wherein the curves (15, 25, 35, 45) have similar meanings as those of Figure 10c, And has a reference circle (C).

In the case of the ORU thickness profile 1862: Figure 20A shows that the curve 1862 is the same as the profile 1862 and the curve 1862A is the IB-flattened thickness profile of the curve 1862 and the curve 1862W is the Is a resonance wavelength for an IB-planarized thickness profile in an oblique optical geometry, and a baseline (? C) is a composite graph representing a critical wavelength at 645 nm; Figure 20B graphically illustrates the slope of the IB-planarized thickness profile 1862A as a function of the resonant wavelength as defined by curve 1862W as curve 1862S and the first region 2001 of 450 to 600 nm, A second region 2002 of 600 to 645 nm, and a reference line lambda c at 645 nm; Figure 20c graphically illustrates the color response at the a *, b * color coordinates of the reflective polarizer-absorbing polarizer laminate where the curves (15, 25, 35, 45) have a similar meaning to those of Figure 10c, And has a reference circle (C).

In the case of the ORU thickness profile 1863: Figure 21A shows that the curve 1863 is the same as the profile 1863 and the curve 1863A is the IB-flattened thickness profile of the curve 1863 and the curve 1863W is the Is a resonance wavelength for an IB-planarized thickness profile in an oblique optical geometry, and a baseline (? C) is a composite graph representing a critical wavelength at 645 nm; Figure 21B graphically illustrates the slope of the IB-planarized thickness profile 1863A as a function of the resonant wavelength as defined by the curve 1863W as curve 1863S and the first region 2101 of 450-600nm, A second region 2102 of 600 to 645 nm, and a reference line c at 645 nm; Figure 21c graphically illustrates the color response at the a *, b * color coordinates of the reflective polarizer-absorbing polarizer laminate where the curves (15, 25, 35, 45) have a similar meaning to those of Figure 10c, And has a reference circle (C).

In the case of the ORU thickness profile 1864: Figure 22A shows that the curve 1864 is the same as the profile 1864 and the curve 1864A is the IB-flattened thickness profile of the curve 1864 and the curve 1864W is the Is a resonance wavelength for an IB-planarized thickness profile in an oblique optical geometry, and a baseline (? C) is a composite graph representing a critical wavelength at 645 nm; Figure 22B graphically illustrates the slope of the IB-planarized thickness profile 1864A as a function of the resonant wavelength as defined by the curve 1864W as curve 1864S and the first region 2201 of 450-600nm, A second region 2202 of 600 to 645 nm, and a reference line c at 645 nm; Figure 22c graphically illustrates the color response at the a *, b * color coordinates of the reflective polarizer-absorbing polarizer laminate, where the curves (15, 25, 35, 45) have similar meanings as those of Figure 10c, And has a reference circle (C).

In the case of the ORU thickness profile 1865: Figure 23A shows that the curve 1865 is the same as the profile 1865 and the curve 1865A is the IB-flattened thickness profile of the curve 1865 and the curve 1865W is the IB- Is a resonance wavelength for an IB-planarized thickness profile in an oblique optical geometry, and a baseline (? C) is a composite graph representing a critical wavelength at 645 nm; Figure 23B graphically illustrates the slope of the IB-planarized thickness profile 1865A as a function of the resonant wavelength as defined by curve 1865W as curve 1865S and the first area 2301 of 450-600nm, A second region 2302 of 600 to 645 nm, and a reference line? C at 645 nm; Figure 23c graphically illustrates the color response at the a *, b * color coordinates of the reflective polarizer-absorbing polarizer laminate, where the curves (15, 25, 35, 45) have similar meanings as those of Figure 10c, And has a reference circle (C).

In the case of the ORU thickness profile 1866: Figure 24A shows that the curve 1866 is the same as the profile 1866 and the curve 1866A is the IB-flattened thickness profile of the curve 1866 and the curve 1866W is the Is a resonance wavelength for an IB-planarized thickness profile in an oblique optical geometry, and a baseline (? C) is a composite graph representing a critical wavelength at 645 nm; Figure 24B graphically illustrates the slope of the IB-planarized thickness profile 1866A as a function of the resonant wavelength as defined by curve 1866W as curve 1866S and the first region 2401 of 450 to 600 nm, A second region 2402 of 600 to 645 nm, and a reference line c at 645 nm; Figure 24c graphically illustrates the color response at the a *, b * color coordinates of the reflective polarizer-absorbing polarizer laminate, where the curves (15, 25, 35, 45) have similar meanings as those of Figure 10c, And has a reference circle (C).

25A shows that the curve 1867 is identical to the profile 1867 and the curve 1867A is the IB-flattened thickness profile of the curve 1867 and the curve 1867W is the IB- Is a resonance wavelength for an IB-planarized thickness profile in an oblique optical geometry, and a baseline (? C) is a composite graph representing a critical wavelength at 645 nm; Figure 25B graphically shows the slope of the IB-planarized thickness profile 1867A as a function of the resonant wavelength as defined by curve 1867W as curve 1867S and shows a first region 2501 of 450 to 600 nm, A second region 2502 of 600 to 645 nm, and a reference line c at 645 nm; Figure 25c graphically illustrates the color response at the a *, b * color coordinates of the reflective polarizer-absorbing polarizer laminate, where the curves (15, 25, 35, 45) have similar meanings as those of Figure 10c, And has a reference circle (C).

In the case of the ORU thickness profile 1868: Figure 26a shows that the curve 1868 is the same as the profile 1868 and the curve 1868A is the IB-flattened thickness profile of the curve 1868 and the curve 1868W is the Is a resonance wavelength for an IB-planarized thickness profile in an oblique optical geometry, and a baseline (? C) is a composite graph representing a critical wavelength at 645 nm; Figure 26B graphically illustrates the slope of the IB-planarized thickness profile 1868A as a function of the resonant wavelength as defined by curve 1868W as curve 1868S and shows a first area 2601 of 450 to 600 nm, A second region 2602 of 600 to 645 nm, and a reference line? C at 645 nm; Figure 26c graphically illustrates the color response at the a *, b * color coordinates of the reflective polarizer-absorbing polarizer laminate, where the curves (15, 25, 35, 45) have similar meanings as those of Figure 10c, And has a reference circle (C).

The results of the slope ratios for the embodiments of Figure 18 are summarized in Table 3, where the " slope ratio " has the same meaning as in Table 2 above.

[Table 3]

The color responses of these embodiments to the observer at a highly inclined critical viewing angle are shown in Figures 19c, 20c, 21c, ... Is best evaluated by inspection of the color response curves in Figure 26C. Briefly summarized, the color trajectories for all of these embodiments remain within acceptable limits.

27 and related Figures 28A-30C demonstrate the application of these same principles to more relevant (modeled) embodiments of the TOP reflective polarizers and their laminates with high contrast absorption polarizers. Similar to the embodiments of Figures 9 and 18, the TOP reflective polarizer embodiments of Figure 27 also have exactly 152 ORUs, each of which has refractive indices of only two microlayers as provided in Table 1 above . Figure 27 shows three different, but related, ORU physical thickness profiles 2761, 2762, 2763, any of which can be readily employed in a TOP reflective polarizer. The thickness profile 2762 is of a linear shape, i.e., a constant slope, from the first ORU (# 1) with a physical thickness of about 108 nm to the last ORU (# 152) with a physical thickness of about 255 nm. Other thickness profiles 2761, 2763 are also linear, but are related to thickness profile 2762 by a simple scaling factor. Profile 2761 is derived by multiplying profile 2762 by a scaling factor of 95%. Profile 2763 is derived by multiplying profile 2762 by a scaling factor of 105%.

Each of these ORU thickness profiles was then analyzed in substantially the same manner as described above with respect to Figures 9 to 26c, and this analysis will not be repeated here to avoid unnecessary repetition.

In the case of the ORU thickness profile 2761: Figure 28A shows that the curve 2761 is the same as the profile 2761 and the curve 2761A is the IB-flattened thickness profile of the curve 2761 and the curve 2761W is the Is a resonance wavelength for an IB-planarized thickness profile in an oblique optical geometry, and a baseline (? C) is a composite graph representing a critical wavelength at 645 nm; Figure 28B graphically illustrates the slope of the IB-planarized thickness profile 2761A as a function of the resonant wavelength as defined by curve 2761W as curve 2761S and shows the first area 2801 of 450 to 600 nm, A second region 2802 of 600 to 645 nm, and a reference line c at 645 nm; Figure 28c graphically illustrates the color response at the a *, b * color coordinates of the reflective polarizer-absorbing polarizer laminate, where the curves 15, 25, 35 have similar meanings as those of Figure 10c, (C).

In the case of ORU thickness profile 2762: Figure 29A shows that curve 2762 is the same as profile 2762, curve 2762A is the IB-flattened thickness profile of curve 2762, curve 2762W is the Is a resonance wavelength for an IB-planarized thickness profile in an oblique optical geometry, and a baseline (? C) is a composite graph representing a critical wavelength at 645 nm; Figure 29B graphically shows the slope of the IB-planarized thickness profile 2762A as a function of the resonant wavelength as defined by curve 2762W as curve 2762S and shows the first region 2901 of 450-600nm, A second region 2902 of 600 to 645 nm, and a reference line? C at 645 nm; Figure 29c graphically illustrates the color response at the a *, b * color coordinates of the reflective polarizer-absorbing polarizer laminate, where the curves (15, 25, 35) have similar meanings to those of Figure 10c, (C).

In the case of the ORU thickness profile 2763: Fig. 30A shows that the curve 2763 is the same as the profile 2763, the curve 2763A is the IB-flattened thickness profile of the curve 2763, and the curve 2763W is the Is a resonance wavelength for an IB-planarized thickness profile in an oblique optical geometry, and a baseline (? C) is a composite graph representing a critical wavelength at 645 nm; Figure 30B graphically shows the slope of the IB-flattened thickness profile 2763A as a function of the resonant wavelength as defined by curve 2763W as curve 2763S and shows the first region 3001 of 450 to 600 nm, A second region 3002 of 600 to 645 nm, and a reference line? C at 645 nm; Figure 30C graphically illustrates the color response at the a *, b * color coordinates of the reflective polarizer-absorbing polarizer laminate where the curves (15, 25, 35, 45) have a similar meaning to those of Figure 10c, And has a reference circle (C).

The results of the slope ratios for the embodiments of Figure 27 are summarized in Table 4, where the " slope ratio " has the same meanings as in Tables 2 and 3 above.

[Table 4]

The color response of these embodiments to the observer at a highly oblique critical viewing angle is best appreciated by inspection of the color response curves in Figures 28c, 29c, and 30c. Briefly summarized, the color locus of Figure 28C (for ORU thickness profile 2761) produces a significantly unacceptable red color; The color traces of Figures 29c and 30c (for ORU thickness profiles 2762 and 2763, respectively) are kept within acceptable limits.

Examples and Comparative Examples

및 텐터링(tentering)을 포함하는 절차들에 의해 연속 필름 라인들 상에서 일부 중합체 기반 TOP 반사 편광기 필름들을 제조하였다. 그러한 필름들, 및 일부 경우에는 정렬된 높은 콘트라스트 흡수 편광기와 그러한 필름의 라미네이트들을 또한 시험하였다. 시험의 일부는 미세층 적층물의 두께 프로파일을 AFM 디바이스로 측정하는 것을 수반하였다. 다른 시험은, 고도로 경사진 광학 기하형상들에서 라이트 테이블(light table) 상에서, 편광기 필름의 조각 또는 그의 라미네이트를 관찰하는 것을 수반하였다.Polymer co-extrusion through feed block,

And some polymer-based TOP reflective polarizer films on continuous film lines by procedures including tentering. Such films, and in some cases aligned high contrast absorbers and laminates of such films were also tested. Part of the testing involved measuring the thickness profile of the microlayer stack with an AFM device. Other tests involved observing a piece of polariser film or a laminate thereof on a light table in highly graded optical geometry.

In the first case, referred to herein as the " embodiment ", the biaxially birefringent microlayers of the microlayer packet comprise LmPEN as described above and the isotropic microlayers of the microlayer packet are made of PETg GN071 Of Eastman Chemicals) and an amorphous blend of 58% and 42% weight fractions of LmPEN, respectively, according to known multilayer optical film manufacturing techniques. The refractive indices of these polymers were similar to those of Table 1. For example, an axial rod heater as described in U.S. Patent No. 6,783,349 (Neavin et al.) Was employed in the feed block, and a temperature profile along the axial rod heater was used, And thus also some control over the ORU thickness profile in the finished TOP reflective polarizer film. The microlayer packet in such a film contains 152 ORUs, and each ORU has one biaxially birefringent microlayer and one isotropic microlayer. The physical thickness of the TOP reflective polarizer was about 31 micrometers. The TOP reflective polarizer of the example provided a broad band reflectance for vertical incident light polarized along the minor axis, the pass axis, and the blocking axis, and the reflectance for such normal incident polarized light was greater than 90% at 430 nm to 650 nm.

The layer thicknesses in the finished film were measured with an AFM device. The raw AFM thickness output was adjusted using an averaging technique to filter the noise and obtain more accurate thickness values. The resulting measured thicknesses of ORUs are plotted as an ORU physical thickness profile 3161 in FIG. Examination of the graph showed that the microlayer packet had a first end at ORU # 1 and a second end at ORU # 151 and the ORUs near the second end were larger than the average physical thickness of the ORUs near the first end Physical thickness.

Analysis on profile 3161 was performed in substantially the same manner as described with respect to the other embodiments above. In this regard: FIG. 32A shows that the curve 3161 is identical to the profile 3161, the curve 3161A is the IB-flattened thickness profile of the curve 3161, and the curve 3161W is the IB- Gt; is a resonant wavelength for an IB-planarized thickness profile at &lt; RTI ID = 0.0 &gt; 1, &lt; / RTI &gt; Figure 32B graphically shows the slope of the IB-planarized thickness profile 3161A as a function of the resonant wavelength as defined by curve 3161W as curve 3161S and is plotted as a function of the first region 3201 of 450 to 600 nm, A second region 3202 of 600 to 645 nm, and a reference line c at 645 nm; Figure 32c shows a schematic view of an OLT having a reflective polarizer (as characterized by profile 3161), a high contrast absorption polarizer (contrast = 1000) aligned, and an end of packet with substantially thicker ORUs having substantially thinner ORUs B * color coordinates of the (modeled) laminate of the TOP reflective polarizer oriented so that it is closer to the absorption polarizer than the end of the packet, where the curves (? 15,? 25,? 35,? 45 Has a similar meaning to those of Fig. 10C, and has a reference circle C. Fig.

The slope ratio for the examples, calculated in the same manner as the slope ratios in Tables 2, 3 and 4, was 1.34. This value, which is less than 1.8, is consistent with the observation that the color response curves in Figure 32c are maintained within substantially acceptable limits, exhibiting acceptable color uniformity behavior and maintaining substantially white within a high critical viewing angle range.

Physical samples of the TOP reflective polarizer film of the examples were also visually examined and observed on a light table. The clear glass was laminated to the San Ritz 5618 Absorbing Polarizer (San Ritz, Tokyo, Japan) using an adhesive, a component of the San Ritz 5618 Polarizer. The TOP reflective polarizer film was then laminated to an absorbance polarizer using an optically clear adhesive (OCA 8171 from 3M, St. Paul, MN, USA). To observe the color characteristics of these laminates at various angles, a diffuse light table using white LEDs of the type commonly found in LCD backlights was used. The laminate was placed on the light table with the reflective polarizer side down. The laminate was then observed over the entire hemisphere. Exemplary films did not exhibit inadequate colors or exhibit color uniformity even when observed at the most severe angles (? = 80 degrees and? = 15, 25, 35, and 45 degrees). An exemplary laminate was compared to another laminate made using a reflective polarizer contained within a commercialized on-glass reflective polarizer (APCF from Nitto Denko, Tokyo, Japan). The laminate made using the APCF reflective polarizer was constructed as the same layers as the laminate of the Example: glass / adhesive / absorbing polarizer / adhesive / reflective polarizer, wherein the absorbing polarizer was the same as used in the laminate of the example , Where the reflective polarizer was an APCF reflective polarizer). When observed at the above-mentioned angles, both of the laminates had very small color shifts along the angle and very small spatial color uniformity and were judged to have similar strength.

In another case referred to herein as " Comparative Example 1 ", the biaxially birefringent microlayers of the microlayer packet include LmPEN as described above, and the isotropic microlayers of the microlayer packet are made of PETg GN071 (Knoxville, Of Eastman Chemicals) and an amorphous blend of 58% and 42% weight fractions of LmPEN, respectively, according to known multilayer optical film manufacturing techniques. The refractive indices of these polymers were similar to those of Table 1. The microlayer packet in such a film contains 152 ORUs, and each ORU has one biaxially birefringent microlayer and one isotropic microlayer. The physical thickness of the TOP reflective polarizer was about 31 micrometers.

The layer thicknesses in the finished film were measured with an AFM device. The raw AFM thickness output was adjusted using an averaging technique to filter the noise and obtain more accurate thickness values. The resulting measured thicknesses of the ORUs are plotted as an ORU physical thickness profile 3361 in FIG. Examination of the graph showed that the microlayer packet had a first end at ORU # 1 and a second end at ORU # 151 and the ORUs near the second end were larger than the average physical thickness of the ORUs near the first end Physical thickness.

Analysis for profile 3361 was performed in substantially the same manner as described with respect to the other embodiments above. 34A shows that the curve 3361 is the same as the profile 3361 and the curve 3361A is the IB-flattened thickness profile of the curve 3361 and the curve 3361W is the IB- Gt; is a resonant wavelength for an IB-planarized thickness profile at &lt; RTI ID = 0.0 &gt; 1, &lt; / RTI &gt; Figure 34B graphically illustrates the slope of the IB-planarized thickness profile 3361A as a function of the resonant wavelength as defined by curve 3361W as curve 3361S and is plotted against a first region 3401 of 450 to 600 nm, A second region 3402 of 600 to 645 nm, and a reference line? C at 645 nm; FIG. 34C shows a schematic view of an OLT having a reflective polarizer (as characterized by profile 3361), an array of high contrast absorption polarizers (contrast = 1000), and ends of packets with substantially thicker ORUs having substantially thinner ORUs B * color coordinates of the (modeled) laminate of the TOP reflective polarizer oriented so that it is closer to the absorption polarizer than the end of the packet, where the curves (? 15,? 25,? 35,? 45 Has a similar meaning to those of Fig. 10C, and has a reference circle C. Fig.

The slope ratio for Comparative Example 1, calculated in the same manner as the slope ratios in Tables 2, 3, and 4, was 2.62. This value, which is greater than 1.8, is consistent with the observation that the color response curves in Figure 34C exhibit unacceptable color uniformity behavior and produce a white-to-yellow effect within a high critical viewing angle range.

Physical samples of the TOP reflective polarizer film of Comparative Example 1 were also visually examined and observed on a light table. The clear glass was laminated to the San Ritz 5618 Absorbing Polarizer (San Ritz, Tokyo, Japan) using an adhesive, a component of the San Ritz 5618 Polarizer. The film of Comparative Example 1 was then laminated to an absorbance polarizer using an optically clear adhesive (OCA 8171 from 3M, St. Paul, MN). To observe the color characteristics of these laminates at various angles, a diffuse light table using white LEDs of the type commonly found in LCD backlights was used. The laminate was placed on the light table with the reflective polarizer side down. The laminate was then observed over the entire hemisphere. The laminate of Comparative Example 1 exhibited inadequate colors when viewed in at least some of the most severe angles (? = 80 degrees and? = 15, 25, 35, and 45 degrees). When the laminate of Comparative Example 1 was compared to a laminate made using an APCF reflective polarizer (described above), the laminate of Comparative Example 1 had much more severe color and spatial color variations at angles, It was judged too severe to be considered for use.

In another case, referred to herein as " Comparative Example 2, " the biaxially birefringent microlayers of the microlayer packet comprise LmPEN and the isotropic microlayers of the microlayer packet are of PETg GN071 (Eastman Chemicals, ) And an amorphous blend of 58% and 42% weight fractions of LmPEN, respectively, according to known multilayer optical film manufacturing techniques. The TOP reflective polarizer film of this Comparative Example 2 is substantially similar to the reflective polarizer film described in column 10, lines 9 to 46 of US Pat. No. 7,791,687 (Weber et al.) And in FIG. 9 thereof. The refractive indexes of the birefringent polymer were nx = 1.820, ny = 1.575, and nz = 1.560, and the refractive index of the isotropic polymer was 1.595. The microlayer packet in such a film contains 138 ORUs, and each ORU has one biaxially birefringent microlayer and one isotropic microlayer. The physical thickness of the TOP reflective polarizer was 31 micrometers.

The layer thicknesses in the finished film were measured with an AFM device. The raw AFM thickness output was adjusted using an averaging technique to filter the noise and obtain more accurate thickness values. The resulting measured thicknesses of the ORUs are plotted as an ORU physical thickness profile 3561 in FIG. 35, which is substantially similar to FIG. 9 of the '687 Weber et al. Patent. Examination of the graph showed that the microlayer packet had a first end at ORU # 1 and a second end at ORU # 137 and the ORUs near the second end were larger than the average physical thickness of the ORUs near the first end Physical thickness.

Analysis on the profile 3561 was performed in substantially the same manner as described with respect to the other embodiments above. 36A shows that the curve 3561 is the same as the profile 3561 and the curve 3561A is the IB-flattened thickness profile of the curve 3561 and the curve 3561W is the IB- Gt; is a resonant wavelength for an IB-planarized thickness profile at &lt; RTI ID = 0.0 &gt; 1, &lt; / RTI &gt; Figure 36B graphically illustrates the slope of the IB-planarized thickness profile 3561A as a function of the resonant wavelength as defined by curve 3561W as curve 3561S and shows a first region 3601 of 450 to 600 nm, A second region 3602 of 600 to 645 nm, and a reference line? C at 645 nm; Figure 36c shows a schematic view of an OLT having a reflective polarizer (as characterized by profile 3561), an array of high contrast absorption polarizers (contrast = 1000), and ends of packets with substantially thicker ORUs having substantially thinner ORUs B * color coordinates of the (modeled) laminate of the TOP reflective polarizer oriented so that it is closer to the absorption polarizer than the end of the packet, where the curves (? 15,? 25,? 35,? 45 Has a similar meaning to those of Fig. 10C, and has a reference circle C. Fig.

The slope ratio for Comparative Example 2, calculated in the same manner as the slope ratios in Tables 2, 3, and 4, was 1.91. This value, which is greater than 1.8, is consistent with the observation that the color response curves in Figure 36C exhibit unacceptable color uniformity behavior and produce a white-to-red effect within a high critical viewing angle range.

Physical samples of the TOP reflective polarizer film of Comparative Example 2 were also visually examined and observed on a light table. The clear glass was laminated to the San Ritz 5618 Absorbing Polarizer (San Ritz, Tokyo, Japan) using an adhesive, a component of the San Ritz 5618 Polarizer. The film of Comparative Example 2 was then laminated to an absorbance polarizer using an optically clear adhesive (OCA 8171 from 3M, St. Paul, Minn.). To observe the color characteristics of these laminates at various angles, a diffuse light table using white LEDs of the type commonly found in LCD backlights was used. The laminate was placed on the light table with the reflective polarizer side down. The laminate was then observed over the entire hemisphere. The laminate of Comparative Example 2 exhibited inadequate colors when viewed in at least some of the most severe angles (? = 80 degrees and? = 15, 25, 35, and 45 degrees). When the laminate of Comparative Example 2 is compared to a laminate made using an APCF reflective polarizer (described above), the laminate of Comparative Example 2 has much more severe color and spatial color variations at angles, It was judged too severe to be considered for use.

The present inventors have also found that the reflective polarizer can be absorbed in the laminate to achieve the lowest level of undesirable visible color at high tilt angles in the white state of the display (in addition to the low color at normal incidence and mid-tilt angles) You will want to deal with the question of how to be oriented with respect to the polarizer. The present inventors have found that the side of the TOP polarizer with thicker ORUs, taking into account that there is a gradient along the thickness axis of the polarizer from predominantly thinner ORUs to predominantly thicker ORUs in the microlayer packet, Such undesirable visible color is substantially reduced to an acceptable level by orienting the TOP polarizer such that the thinner microlayer end faces away from (and front of the display) and faces the thinner microlayer end away from the absorber polarizer and back of the display . This is referred to as thick-layers-up orientation, and the opposite orientation as thin-layers-up orientation, the laminate of Example, the laminate of Comparative Example 1, and COMPARATIVE EXAMPLE 2 The laminate used an orientation with all the thick layers up. However, each of these three laminates was also examined in a thin layer-up orientation reconstructed using a diffuse light table. In each case, the color performance at the most severe observation geometry (e.g.,? = 80 degrees and? = 15, 25, 35, and 45 degrees) was inferior to the color performance at the orientation with thicker layers .

The following is a non-exhaustive list of some of the items discussed and described herein.

Item 1 is a laminate, the laminate is

A packet of reflective polarizer-microlayers having only one packet of the microlayers that reflect and transmit light by optical interference has a first pass axis (y), a first minor axis (x), and a first pass axis Wherein the first minor axis and the first thickness axis form an xz plane and the packet of microlayers comprises alternating first and second microlayers And the first microlayers are birefringent; And

Absorbing polarizer having a second pass axis and a second blocking axis is attached to the reflective polarizer such that there is no air gap therebetween and the first and second pass shafts are substantially aligned and the absorbance polariser has a contrast ratio of 1000 or more - &lt; / RTI &gt;

Pairs of adjacent first and second microlayers form optical repeat units (ORUs) along a packet of microlayers, wherein the ORUs are arranged in a physical (not shown) fashion with a gradient providing a broad band reflectance for the vertically- Define a thickness profile, and the ORUs have respective resonant wavelengths as a function of physical thickness profile and optical geometry shape;

The ORUs include a first ORU and a last ORU that define opposite ends of the packet, wherein the last ORU is closer to the absorbance polarizer than the first ORU, and the physical thickness profile is such that the ORUs close to the last ORU are closer to the first ORU Have an average physical thickness greater than the average physical thickness;

The intrinsic bandwidth-based boxcar mean of the physical thickness profile yields an IB-planarized thickness profile, wherein the IB-planarized thickness profile is defined in each of the ORUs;

The ORUs,

An ORU 450 having a resonant wavelength for an IB-planarized thickness profile of 450 nm or greater for a tilted optical geometry that P-polarized light is incident on the xz plane at a 80 degree angle of declination - All ORUs disposed on the sides of the ORU 450 having resonant wavelengths less than 450 nm for an IB-planarized thickness profile in an oblique optical geometry;

ORU 600 having a resonant wavelength for an IB-planarized thickness profile of at least 600 nm for an oblique optical geometry - all ORUs placed on the side of an ORU 600 comprising a first ORU have an oblique optical geometry Having a resonant wavelength of less than 600 nm for an IB-planarized thickness profile; And

An ORU 645 having a resonant wavelength for the IB-planarized thickness profile, which may be optionally the same as the last ORU 645 nm for an oblique optical geometry, a side surface of ORU 645 comprising a first ORU 645, Wherein all of the ORUs located in the first layer have resonant wavelengths less than 645 nm for an IB-planarized thickness profile in an oblique optical geometry,

The IB-planarized thickness profile has a first mean slope ranging from ORU 450 to ORU 600 and a second mean slope ranging from ORU 600 to ORU 645, The ratio of the second mean slope to the slope is 1.8 or less.

Item 2 is a laminate of item 1, wherein the IB-flattened thickness profile as evaluated in any given ORU contains substantially only such ORUs that consistently contribute to the reflectivity of the packet at the resonant wavelength of a given ORU.

Item 3 is a laminate of Item 1, wherein the IB-flattened thickness profile as evaluated in any given ORU comprises a predetermined number of ORUs that are nearest neighbors on each side of a given ORU.

Item 4 is the laminate of Item 3, where the predetermined number is 20 or less.

Item 5 is the laminate of Item 3, which has a predetermined number of 5 or more.

Item 6 is the laminate of Item 3, which has a predetermined number of ten.

Item 7 shows that the resonant wavelength of the ORU 450 for the IB-planarized thickness profile is less than 455 nm, the resonant wavelength of the ORU 600 for the IB-planarized thickness profile is less than 605 nm, the IB- Is a laminate of any preceding item, wherein the resonant wavelength of the ORU 645 for the thickness profile is less than 650 nm.

Item 8 is a laminate of any preceding item, wherein the second microlayers are substantially isotropic.

Item 9 is a laminate of any preceding item, wherein the first and second microlayers each comprise different first and second polymeric materials.

Item 10 is a laminate of any preceding item wherein the reflective polarizer has a physical thickness of less than 50 micrometers.

Item 11 is the laminate of item 10, wherein the physical thickness of the reflective polarizer is in the range of 20 to 40 micrometers.

Item 12 is a laminate of any preceding item wherein the laminate consists essentially of a reflective polarizer, an absorbent polarizer, and an adhesive layer that bonds the reflective polarizer to the absorbent polarizer.

Item 13 provides that the packets of the microlayers provide a normal polarized incident light transmittance to the reflective polarizer on average over a wavelength range of 400-700 nm, with a normal incident transmittance of 80% or more for pass-state polarizations and less than 15% It is a laminate of any preceding item.

Item 14 is a reflective polarizer having only one packet of the microlayers that reflect and transmit light by optical interference, wherein the packet of microlayers has a pass axis (y), a minor axis (x) Wherein the first minor axis and the thick axis form an xz plane and the packet of microlayers comprises alternating first and second microlayers, wherein the first microlayers are configured to define a biaxial birefringent ego;

The pairs of adjacent first and second microlayers form optical repeat units (ORUs) along the packet of microlayers, and the ORUs have a physical thickness profile with a gradient that provides a broad band reflectance for the vertically- And the ORUs have respective resonant wavelengths as a function of physical thickness profile and optical geometry shape;

ORUs comprise a first ORU and a last ORU that define opposite ends of the packet and wherein the physical thickness profile is such that ORUs proximate to the last ORU have an average physical thickness greater than the average physical thickness of ORUs proximate to the first ORU;

The intrinsic bandwidth-based boxcar mean of the physical thickness profile yields an IB-planarized thickness profile, wherein the IB-planarized thickness profile is defined in each of the ORUs;

The ORUs,

An ORU 450 having a resonant wavelength for an IB-planarized thickness profile of 450 nm or greater for a tilted optical geometry that P-polarized light is incident on the xz plane at a 80 degree angle of declination - All ORUs disposed on the sides of the ORU 450 having resonant wavelengths less than 450 nm for an IB-planarized thickness profile in an oblique optical geometry;

ORU 600 having a resonant wavelength for an IB-planarized thickness profile of at least 600 nm for an oblique optical geometry - all ORUs placed on the side of an ORU 600 comprising a first ORU have an oblique optical geometry Having a resonant wavelength of less than 600 nm for an IB-planarized thickness profile; And

An ORU 645 having a resonant wavelength for the IB-planarized thickness profile, which may be optionally the same as the last ORU 645 nm for an oblique optical geometry, a side surface of ORU 645 comprising a first ORU 645, Wherein all of the ORUs located in the first layer have resonant wavelengths less than 645 nm for an IB-planarized thickness profile in an oblique optical geometry,

The IB-planarized thickness profile has a first mean slope ranging from ORU 450 to ORU 600 and a second mean slope ranging from ORU 600 to ORU 645, The ratio of the second mean slope to the slope is 1.8 or less.

Item 15 is the polarizer of item 14, wherein the IB-flattened thickness profile as evaluated at any given ORU contains substantially only such ORUs that consistently contribute to the reflectivity of the packet at the resonant wavelength of the given ORU.

Item 16 is the polarizer of Item 14, wherein the IB-flattened thickness profile as evaluated in any given ORU comprises a predetermined number of ORUs that are nearest neighbors on each side of a given ORU.

Item 17 is the polarizer of Item 16, wherein the predetermined number is 20 or less.

Item 18 shows that the resonant wavelength of the ORU 450 for the IB-planarized thickness profile is less than 455 nm, the resonant wavelength of the ORU 600 for the IB-planarized thickness profile is less than 605 nm, And the polarizer of any of items 14 to 17, wherein the resonance wavelength of the ORU 645 for the thickness profile is less than 650 nm.

Item 19 is a polarizer of any of items 14 to 18, wherein the second microlayers are substantially isotropic.

Item 20 is a laminate, the laminate is

The reflective polarizer-passing axis of item 14 is a first pass axis and the minor axis is a first minor axis; And

Absorbing polarizer having a second pass axis and a second blocking axis is attached to the reflective polarizer such that there is no air gap therebetween and the first and second pass shafts are substantially aligned and the absorbance polariser has a contrast ratio of 1000 or more - &lt; / RTI &gt;

The last ORU is closer to the absorption polarizer than the first ORU.

Unless otherwise indicated, all numbers expressing quantities, measurements of properties, etc. used in the specification and claims are to be understood as modified by the term " about ". Accordingly, unless indicated to the contrary, the numerical parameters set forth in the specification and claims are approximations that may vary depending upon the desired properties desired by one of ordinary skill in the art using the teachings of this application. Rather than as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Where numerical ranges and parameters describing the broad scope of the invention are approximations, if any numerical values are described in the specific examples described herein, they are reported as reasonably as possible. However, any numerical value may possibly include errors associated with the test or measurement limit.

It should be understood by those skilled in the art that various changes and modifications of the present invention will be apparent to those skilled in the art without departing from the spirit and scope of the present invention and that the present invention is not limited to the exemplary embodiments described herein. The reader should be aware that, unless otherwise indicated, the features of one disclosed embodiment may also be applied to all other disclosed embodiments. It is also to be understood that all of the US patents, patent application publications, and other patents and non-patent literature referred to herein are incorporated by reference to the extent not inconsistent with the foregoing disclosure.

Claims (20)

As a laminate,
A packet of reflective polarizer-microlayers with only one packet of microlayers reflecting and transmitting light by optical interference has a first pass axis (y), a first primary axis (x) And a first pass axis and a first thickness axis (z) perpendicular to the first minor axis, wherein the first minor axis and the first thickness axis form an xz plane, and wherein the packets of the microlayers Comprises alternating first and second microlayers, wherein the first microlayers are birefringent; And
Absorbing polarizer having a second pass axis and a second blocking axis is attached to the reflective polarizer such that there is no air gap therebetween and the first and second pass shafts are substantially aligned and the absorbance polariser has a contrast ratio of 1000 or more and having a contrast ratio,
Pairs of adjacent first and second microlayers form optical repeating units (ORUs) along the packet of microlayers, wherein the ORUs provide broadband reflectivity for the vertically polarized light incident along the first blocking axis And wherein the ORUs have respective resonant wavelengths as a function of a physical thickness profile and an optical geometry shape;
The ORUs include a first ORU and a last ORU that define opposite ends of the packet, wherein the last ORU is closer to the absorbance polarizer than the first ORU, and the physical thickness profile is such that the ORUs close to the last ORU are closer to the first ORU Have an average physical thickness greater than the average physical thickness;
The intrinsic bandwidth-based boxcar average of the physical thickness profile yields an IB-planarized thickness profile, wherein the IB-planarized thickness profile is defined in each of the ORUs;
The ORUs,
The ORU 450 with a resonant wavelength for an IB-planarized thickness profile of 450 nm or greater for a tilted optical geometry that is incident on the xz plane at a polar angle (?) Of 80 degrees P- All ORUs disposed on the side of the ORU 450 including the first ORU have resonant wavelengths less than 450 nm for the IB-planarized thickness profile in the tilted optical geometry;
ORU 600 having a resonant wavelength for an IB-planarized thickness profile of at least 600 nm for an oblique optical geometry - all ORUs placed on the side of an ORU 600 comprising a first ORU have an oblique optical geometry Having a resonant wavelength of less than 600 nm for an IB-planarized thickness profile; And
An ORU 645 having a resonant wavelength for the IB-planarized thickness profile, which may be optionally the same as the last ORU 645 nm for an oblique optical geometry, a side surface of ORU 645 comprising a first ORU 645, Wherein all of the ORUs located in the first layer have resonant wavelengths less than 645 nm for an IB-planarized thickness profile in an oblique optical geometry,
The IB-planarized thickness profile has a first mean slope ranging from ORU 450 to ORU 600 and a second mean slope ranging from ORU 600 to ORU 645, Wherein the ratio of the second average slope to the slope is less than or equal to 1.8. The laminate of claim 1, wherein the IB-planarized thickness profile as assessed in any given ORU comprises substantially only such ORUs that consistently contribute to the reflectivity of the packet at a resonant wavelength of a given ORU. The laminate of claim 1, wherein the IB-planarized thickness profile as evaluated in any given ORU comprises a predetermined number of ORUs that are nearest neighbors on each side of a given ORU. 4. The laminate of claim 3, wherein the predetermined number is 20 or less. 4. The laminate of claim 3, wherein the predetermined number is at least 5. The laminate of claim 3, wherein the predetermined number is 10. The method of claim 1, wherein the resonant wavelength of the ORU (450) for the IB-planarized thickness profile is less than 455 nm, the resonant wavelength of the ORU (600) for the IB-planarized thickness profile is less than 605 nm, Wherein the resonant wavelength of the ORU (645) for the planarized thickness profile is less than 650 nm. The laminate of claim 1, wherein the second microlayers are substantially isotropic. The laminate of claim 1, wherein the first and second microlayers each comprise different first and second polymeric materials. The laminate of claim 1, wherein the reflective polarizer has a physical thickness of less than 50 micrometers. 11. The laminate of claim 10, wherein the physical thickness of the reflective polarizer is in the range of 20 to 40 micrometers. The laminate of claim 1, wherein the laminate consists essentially of a reflective polarizer, an absorbent polarizer, and an adhesive layer that bonds the reflective polarizer to the absorbent polarizer. The method of claim 1, wherein the packets of microlayers provide a normal incidence transmittance to the reflective polarizer of at least 80% for transit state polarization and less than 15% for interception state polarization over a wavelength range of 400-700 nm on average Laminate, made. 1. A reflective polarizer having only one packet of microlayers that reflect and transmit light by optical interference, the packet of microlayers having a pass axis (y), a minor axis (x), and a thickness perpendicular to the minor axis The first minor axis and the thick axis forming an xz plane, the packet of microlayers comprising alternating first and second microlayers, the first microlayers being biaxially birefringent;
The pairs of adjacent first and second microlayers form optical repeat units (ORUs) along the packet of microlayers, and the ORUs have a physical thickness profile with a gradient that provides a broad band reflectance for the vertically- And the ORUs have respective resonant wavelengths as a function of physical thickness profile and optical geometry shape;
ORUs comprise a first ORU and a last ORU that define opposite ends of the packet and wherein the physical thickness profile is such that ORUs proximate to the last ORU have an average physical thickness greater than the average physical thickness of ORUs proximate to the first ORU;
The intrinsic bandwidth-based boxcar mean of the physical thickness profile yields an IB-planarized thickness profile, wherein the IB-planarized thickness profile is defined in each of the ORUs;
The ORUs,
An ORU 450 having a resonant wavelength for an IB-planarized thickness profile of 450 nm or more for a tilted optical geometry that is incident on the xz plane at a polarization angle of? All ORUs disposed on the sides of the containing ORU 450 have resonant wavelengths less than 450 nm for the IB-planarized thickness profile in the tilted optical geometry;
ORU 600 having a resonant wavelength for an IB-planarized thickness profile of at least 600 nm for an oblique optical geometry - all ORUs placed on the side of an ORU 600 comprising a first ORU have an oblique optical geometry Having a resonant wavelength of less than 600 nm for an IB-planarized thickness profile; And
An ORU 645 having a resonant wavelength for the IB-planarized thickness profile, which may be optionally the same as the last ORU 645 nm for an oblique optical geometry, a side surface of ORU 645 comprising a first ORU 645, Wherein all of the ORUs located in the first layer have resonant wavelengths less than 645 nm for an IB-planarized thickness profile in an oblique optical geometry,
The IB-planarized thickness profile has a first mean slope ranging from ORU 450 to ORU 600 and a second mean slope ranging from ORU 600 to ORU 645, Wherein the ratio of the second mean slope to the slope is less than or equal to 1.8. 15. The polariser of claim 14, wherein the IB-planarized thickness profile as assessed in any given ORU comprises substantially only such ORUs that consistently contribute to the reflectivity of the packet at a resonant wavelength of a given ORU. 15. The polariser of claim 14, wherein the IB-planarized thickness profile as evaluated in any given ORU comprises a predetermined number of ORUs that are closest neighbors on each side of a given ORU. 17. The polariser of claim 16, wherein the predetermined number is 20 or less. 15. The method of claim 14, wherein the resonant wavelength of the ORU (450) for the IB-planarized thickness profile is less than 455 nm, the resonant wavelength of the ORU (600) for the IB-planarized thickness profile is less than 605 nm, Wherein the resonant wavelength of the ORU (645) for the planarized thickness profile is less than 650 nm. 15. The polariser of claim 14, wherein the second microlayers are substantially isotropic. As a laminate,
The reflective polarizer-passing axis of claim 14 being a first pass axis and the minor axis being a first minor axis; And
Absorbing polarizer having a second pass axis and a second blocking axis is attached to the reflective polarizer such that there is no air gap therebetween and the first and second pass shafts are substantially aligned and the absorbance polariser has a contrast ratio of 1000 or more - &lt; / RTI &gt;
The last ORU is closer to the absorbance polariser than the first ORU.

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